Introduction
While this article chronicles Apocalypse and his many descendants, it is important to note that this is not merely a family tree in the traditional sense. It is unclear just how many generations removed most of Apocalypse’s descendants are from him. Throughout history, Apocalypse’s direct blood relatives have made their presence known. Most of them are members of the covert organization called Clan Akkaba. However, leadership of the Clan has recently changed hands and currently contains a number of members that are not related to Apocalypse.
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Ancient Egypt
The man who would one day be called Apocalypse was born approximately 5,000 years ago in Akkaba, a settlement near Amentet and the very edge of the Valley of the Kings, in ancient Egypt. After his birth, he was considered an abomination by his tribe and cast out, left to die in the desert. The Sandstormers, a rival tribe, massacred the people of Akkaba in search of a prize. This prize turned out to be the abandoned boy. The leader of the Sandstormers, Baal, had learned of the boy by viewing a special stone from the future called "Eye of the Ages," which he had stolen from the time traveler Rama Tut. The stone had revealed that En Sabah Nur was destined for greatness and referred to him as the "Child of Destiny." To this end, Baal adopted the baby and named him En Sabah Nur.
As En Sabah Nur grew, Baal taught him the philosophy of the Sandstormers - "survival of the fittest." During this time, Rama Tut continued to search for En Sabah Nur. When he eventually learned his location, he sent his general, Ozymandias, to the Sandstormer camp. In the ensuing battle, Ozymandias slaughtered the entire Sandstormer tribe, save Baal and En Sabah Nur. At the time, Baal had been showing En Sabah Nur the Eye of the Ages which was hidden in caves. As a result of the battle, the two became trapped and the elderly Baal died. When En Sabah Nur eventually reached the surface weeks later, he was greeted by Logos, a vizier of Rama Tut. Logos agreed to hide En Sabah Nur, provided he rid Egypt of Rama Tut and Ozymandias. En Sabah Nur accepted and was hidden among the slaves of Egypt.
Now within Rama Tut's kingdom, En Sabah Nur waited. However, while working on the pyramid, he spotted Ozymandias and unable to stay hidden, he screamed out his name. Disgusted that a lowly slave would speak his name, Ozymandias whipped En Sabah Nur off the pyramid. En Sabah Nur fell to his death but was resurrected by the goddess Isis. After Nur’s resurrection, Ozymandias attempted to kill him again but once more Nur was saved, this time by Ozymandias' sister, Nephri. Unfortunately for En Sabah Nur, his luck did not last and he was captured by Rama Tut, along with Nephri and Logos. Tut offered to make En Sabah Nur his heir, which was the main reason he had traveled to this time period. However, En Sabah Nur refused and was sentenced to death. Miraculously, he managed to escape his execution yet again. After his escape, En Sabah Nur decided to rename himself Apocalypse.
The arrival of the time-traveling Fantastic Four was very fortunate for En Sabah Nur. Though initially mind-controlled by Rama Tut, the heroes broke free and began to wreak havoc in Tut's city. Having already lost En Sabah Nur and now having to deal with the Fantastic Four, Tut abandoned the time period. With Tut gone, En Sabah Nur sought out his only surviving rival: Ozymandias. Finding him in Rama Tut's hidden sanctum, En Sabah Nur used the Eye of Ages on Ozymandias, transforming the general into an immortal, blind seer made of stone and totally subservient to him. Triumphant, Apocalypse began to view the Egyptians themselves as weak and eventually decided to abandon them. Before this, he sired numerous children who formed the first generation of Clan Akkaba. [Rise of Apocalypse #1-4]
Apocalypse (En Sabah Nur)First appearance: Marvel Graphic Novel #17 (in disguise), X-Factor (1st series) #5 (fully revealed)
All Clan Akkaba appearances: Rise of Apocalypse #4, X-Men: Apocalypse vs. Dracula #1-4
Powers: metahuman strength, speed, endurance, reflexes, durability, can absorb outside sources of energy to increase his strength, teleport himself over vast distances, discharge massive amounts of raw plasma, omnimorphic molecular structure that allows him to assume any physical form, shape his limbs into weapons or devices, and alter his size and mass, and a techno-organic factor in his bloodstream, enabling vast regenerative potential
Baal
First appearance: Rise of Apocalypse #1
All Clan Akkaba appearances: none
Powers: none
Ozymandias
First appearance: Uncanny X-Men (1st series) #332
All Clan Akkaba appearances: Rise of Apocalypse #4, X-Men: Apocalypse vs. Dracula #1-4, New Excalibur #9
Powers: human recast out of living stone, giving him enhanced strength and durability, virtual immortality, prescient sight which allows him to carve out present and future from his mind's eye onto stone, and the ability to bring life to and animate his stone carvings and statues
Victorian Era
Apocalypse began to travel the globe and spread his seed. He named these children Clan Akkaba, after his own clan of origin, but he taught them the philosophy of the Sandstormers. Using Tut's technology, Apocalypse would regularly go into hibernation in an effort to extend his life, leaving Ozymandias and Clan Akkaba to do his bidding in his stead. Apocalypse would emerge periodically to make sure the world hadn’t forgotten him and spread his philosophy that only the strong would survive. Indeed, the Clan left their own mark on history. By their own admission, their members not only had a hand in slavery in ancient Egypt, but they were also involved in the destruction of Rome, the French Revolution, and the discovery of America.
Throughout the millennia, the members of Clan Akkaba would "test" each other to gain the title of "Fittest" and to be considered "closest" to Apocalypse.Those whose abilities were most similar to Apocalypse's 
had greater standing in the clan and could join the Inner Council and possibly achieve the title of "Fittest." On the other hand, those whose abilities were not like Apocalypse's were called "lessers" and were considered the lowest of the low within the clan. All members of the clan were tattooed with the clan's symbol. Those who were found to have more of Apocalypse's blood would get a bigger tattoo. [X-Men: Apocalypse vs. Dracula #1]
During the Victorian Era, Clan Akkaba flourished. They were based out of London in a building called Alexandria House. Members included Margaret Slade, who had inherited Apocalypse's molecular rearrangement abilities to a limited degree and had claimed a seat on the Inner Council, along with her two sons, Hamilton and Frederick. Hamilton also inherited Apocalypse's molecular rearrangement abilities but to a much greater degree and was virtually invulnerable. Frederick was the youngest; while he also possessed the same limited molecular rearrangement abilities as his mother, he secretly had an additional ability of his own - teleportation. Ozymandias seemed to favor Frederick and began to train him. Jealous of the attention his brother was getting, Hamilton crushed Frederick's spine while he slept, essentially crippling him. Hamilton then took the title of “Fittest” with little true opposition, save Kabar Brashir, another member of the Inner Council, whose molecular rearrangement abilities were nearly as advanced as Hamilton's.
Another member of the clan at this time was detective and opium addict Jack Starsmore. Considered a "lesser" in the Clan, due to his fire-breathing abilities, Jack's position as a detective became useful in 1897 when several members of the Clan were being murdered. When their leader, Hamilton, disappeared, the Inner Council was forced to summon Apocalypse. The Clan's inner circle was very racially diverse at this time, with representatives from around the world and included a few with gray skin tone. Awakening Apocalypse wasn’t done lightly, as Apocalypse would require a “sacrifice” of a council member as the price for summoning him before his hibernation cycle was complete. In this particular instance, it was a gray-skinned female chosen by Apocalypse upon his awakening. After the council had summoned Apocalypse and paid the “price,” Jack Starsmore burst in. He had been informed by a vampire hunter named Professor Abraham van Helsing that the Clan was under attack by none other than Dracula himself.
While Apocalypse was confirming Van Helsing's claims, the newly-turned Hamilton Slade returned to Alexandria House along with his new master, Dracula. After killing Kabar Brashir outright, Hamilton helped Dracula to transform the assembled members of the Clan into vampires as well. Only Hamilton’s mother, Margaret, and his brother, Frederick were spared this fate. Upon their return to Alexandria House, Apocalypse, Jack Starsmore, Van Helsing and Ozymandias found themselves under attack by the newly sired Clan Akkaba.
If not for Frederick Slade's previously unknown ability to teleport, they would have been slaughtered.
At an unknown country estate, the four prepared for the oncoming onslaught which began at dusk. In a battle that lasted until sunrise, the group prevailed and slaughtered the vampire mutants. They later hunted down and staked those that had managed to escape, with the exception of Hamilton Slade who had made his mother his familiar and fled to Transylvania. Apocalypse's group followed them to Transylvania, where Jack and Frederick managed to kill Hamilton right after he killed his mother, Margaret. Apocalypse also defeated Dracula and went back into hibernation, believing his clan was no more. [X-Men: Apocalypse vs. Dracula #1-4]
Note: In the final issue of Blade (3rd Series) #12, Blade (along with his father Lucas Cross, Hannibal King and Dracula) cast a spell that they believed would give Dracula and Lucas back their souls. The ritual promised to "return essence lost to those undead in graves." However, the men misinterpreted the meaning of the ritual. It didn't give vampires back their souls, instead it restored the lives of all vampires previously destroyed. Considering this fact, it's very possible that Hamilton Slade and his vampire kinsmen are once more amongst the unliving.
Starsmore, JackFirst appearance: X-Men: Apocalypse vs. Dracula #1
Last appearance: mentioned deceased in New Excalibur #9
All Clan Akkaba appearances: X-Men: Apocalypse vs. Dracula #1-4
Powers: spew controlled bursts of flame from his throat
Slade, Hamilton
First appearance: X-Men: Apocalypse vs. Dracula #1
Last appearance: X-Men: Apocalypse vs. Dracula #4 [killed by Frederick Slade]
All Clan Akkaba appearances: X-Men: Apocalypse vs. Dracula #1-4
Powers: control over his molecular structure grants him augmented strength, durability, stretching power, and the ability to morph his hands into different shapes and weapons; later transformed into a vampire
Brashir, Kabar
First appearance: X-Men: Apocalypse vs. Dracula #2
Last appearance: X-Men: Apocalypse vs. Dracula #3 [killed by Hamilton Slade]
All Clan Akkaba appearances: X-Men: Apocalypse vs. Dracula #2-3
Powers: control over his molecular structure enables him to morph his hands into mechanical vice grips
Slade, Margaret
First appearance: X-Men: Apocalypse vs. Dracula #2
Last appearance: X-Men: Apocalypse vs. Dracula #4 [killed by Hamilton Slade]
All Clan Akkaba appearances: X-Men: Apocalypse vs. Dracula #2-4
Powers: control over her molecular structure allows her to morph her hands into metallic talons
Slade, Frederick
First appearance: X-Men: Apocalypse vs. Dracula #2
All Clan Akkaba appearances: X-Men: Apocalypse vs. Dracula #2-4, New Excalibur #9
Powers: control over his molecular structure gives him the ability to morph his hands into bladed weapons, additional teleportation power
UNNAMED MEMBERS OF THE INNER CIRCLE
The Modern Age
Unbeknownst to Apocalypse, Ozymandias decided to continue Clan Akkaba in order to use them against him at some later stage. He hired a prostitute named Miss Ferguson to sleep with the still-crippled Frederick Slade. [X-Men: Apocalypse vs. Dracula #4] This union produced at least one child, most likely a male, who used his mother's maiden name. The child went on to become the direct ancestor of Clarice Ferguson. On Earth 616, Clarice appeared to meet her end against the Phalanx Harvest when she was caught in the wake of her own teleportation power. [X-Men (2nd series) #37] However, Clarice survived and was rescued by the eternal Selene. Selene warped the young girl's mind and used her as a weapon against her former allies, the X-Men. [X Necrosha: The Gathering and X-Force (3rd series) #21-25] Selene was ultimately defeated and the effects to Blink's mind were undone by the combined efforts of Emma Frost and Doctor Strange. Wracked with guilt, Blink decided she needed time to herself. [X-Men: To Serve and Protect #3] She was eventually found by the New Mutants and ultimately decided to join the Jean Grey School of Higher Learning to learn more about her powers. [New Mutants (3rd series) #34-36] In the altered timeline known as the Age of Apocalypse, Blink became a valuable member of the X-Men. This version of Clarice had at least one unnamed brother and mentioned that she came from Cartusia in the Bahamas. [Exiles (1st series) #1] It's not clear if Clarice's brother exists on Earth 616.
Jack Starsmore also went on to have a family. His great-grandson is the former X-Man and Generation X member Chamber aka Jonothan Starsmore. Though much more powerful by far, Chamber obviously inherited a variation of his great-grandfather's fire-breathing abilities. While Chamber was aware of his family's connection to Clan Akkaba from an early age, he never associated with the Clan. After he was depowered during M-Day, Chamber was dramatically injured and lost a large section of his chest. Still active in Clan Akkaba after all these years, Frederick Slade used the blood of Apocalypse to regenerate Chamber's body, leaving him with an "Apocalypse"-like appearance. However, Chamber still rejected the Clan and left them. [Generation M #1, New Excalibur #9] Chamber would later be present on the island of Utopia during Legion's Age of Xreality warp. In this new reality, Chamber had never lost his powers and as such, had not been altered by the Akkaba. When reality was eventually set right, Chamber's original abilities and appearance remained and he seemed to be purged of the physical changes wrought by Clan Akkaba. [X-Men Legacy #245-247, New Mutants (3rd series) #22-24]
Interestingly enough, the members of the modern Clan Akkaba are very ethnically diverse. It is unknown if they are all descendents of Frederick Slade and Jack Starsmore, or whether they originate from other bloodlines spawned by Apocalypse that were not present at the purge of 1897. In addition to Slade, there were nine other clan members from various ethnic & cultural backgrounds. It’s unknown if any of them retained their powers after M-day, as most showed no obvious signs of mutation. There were two exceptions who both sported Apocalypse’s most characteristic traits - blue lips and gray skin. It remains to be seen if these physical traits are merely cosmetic in nature or if these two have retained a fraction of the power of their malevolent sire. [New Excalibur #9]
It’s unclear just how severely Clan Akkaba was affected by M-Day, during which 90-95% of Earth's mutant population lost their powers. However, their numbers appear to be much larger than the few who were instrumental in restoring Chamber to a semblance of health. After the apparent demise of Apocalypse, the Clan attempted to resurrect him via the blood sacrifice of one of their own. Deadpool infiltrated the Clan's Egyptian base but failed to prevent this ritual and was captured. The Clan's new stronghold was staffed with guards, priestesses, and scientists loyal to the Clan. It was not clear whether they were truly descendants of Apocalypse or merely disciples of the Clan. [Uncanny X-Force #1]
Though X-Force failed to prevent the resurrection ritual, Apocalypse was bizarrely reborn as a mere child, with none of his memories. On their lunar base, the Clan was attempting to swiftly re-indoctrinate the young Apocalypse with the Clan's philosophies when they were attacked by X-Force. X-Force fought their way through a score of Clan Akkaba troops in an attempt to find Apocalypse. None of the male members of the Clan's forces displayed any obvious mutant traits. The females, on the other hand, all had “bird-like” heads, which may have been mere decoration. 
At least one of these “avian” females had the ability to project incendiary green energy, though she met her end in battle against Wolverine. It is possible these soldiers were all clones, as all the males and females appeared to be identical. During the battle, they condemned the X-Men as "race traitors" and made other statements that suggested that they were mutants, or at the very least, adherents to Apocalypse's belief in mutant supremacy. Regardless of how many of the Akkaba soldiers still had their mutant abilities, they were outmatched and massacred by X-Force.
After the battle, X-Force managed to reach the reborn Apocalypse. Upon seeing that this new incarnation of Apocalypse was just a child, most of X-Force was in favor of sparing him. New member Fantomex disagreed, believing that this version of Apocalypse was already beyond redemption. He unceremoniously killed the boy before any of the others could act. [Uncanny X-Force #1-4]
With this new Apocalypse dead, Warren Worthington's “Death” persona finally overtook his mind. Warren now saw himself as the “new” Apocalypse and started to find allies amongst the Akkaba to serve him. One of Archangel's allies, Dark Beast, brought him to the Clan's hidden North Pole city, which was populated with a number of Akkaba who were much the same in appearance as those X-Force had just encountered. Among their number, Archangel found William Rolfson, the blood heir of Apocalypse and the son of Autumn Rolfson, Apocalypse's former horseman Famine. Autumn had hidden William from Apocalypse, as she was afraid he might view the boy as a threat and kill him. Archangel, however, didn't view William as a threat but as a weapon. He would later use the boy to kill thousands of innocents in an effort to jumpstart evolution. Terrified that Archangel was going to turn her son into a monster, Autumn, in one final act of valor, attempted to save her son by killing Archangel. Her attempt was unsuccessful and Archangel ripped Autumn apart. William, now operating under the moniker Genocide, appeared to perish in a battle with X-Force and their allies from the Age of Apocalypse reality.
Despite the loss of Genocide during this battle, the tide started to turn in the favor of Archangel and his allies. This forced Fantomex to unveil his smoking gun. Unbeknownst to his teammates, Fantomex had taken a DNA sample off the child Apocalypse and cloned him. The clone was grown at an accelerated rate and was raised in the artificial environment called The World. The clone believed himself to be a farm-boy from Kansas called Evan En Sabah Nur. Fantomex had been pretending to be Evan's “Uncle Cluster” and occasionally entered the artificial reality to train the boy in his powers. Fantomex decided he could no longer wait to unleash Evan and set him against Archangel. The fledgling mutant proved little match for Archangel and was easily defeated. Archangel himself was subsequently defeated by Psylocke. In the aftermath of the battle, X-Force decided to enroll Evan in the Jean Grey School for Higher Learning. [Uncanny X-Force #14-19] Currently, Evan is unaware of his lineage, though his fellow students have already noticed his similarity to Apocalypse. [Wolverine and the X-Men #4]
After Archangel was defeated, the Dark Beast fled to the Clan's Neptune Station with some of Archangel's allies using Apocalypse's ship. It's unclear if any of the Akkaba citizens of the North Pole city managed to escape in the wake of the battle. The Dark Beast mentioned that the Clan was a splintered group, suggesting that there could be additional sects of the Clan active in the world. With no indication of how many children Apocalypse has sired in his long life nor if this latest incarnation of Clan Akkaba was the only branch of his descendants, it's impossible to guess how many of Apocalypse’s direct descendants are currently walking among the children of the atom.
Ferguson, ClariceFirst appearance: Uncanny X-Men (1st series) #317
All Clan Akkaba appearances: none
Powers: manifests spacial-shearing ability as slashways, distortion pulses or portals which can teleport objects or slice them into thousands of jagged pieces
Decibel / Chamber (Jonothan Starsmore)
First appearance: Generation X #1
All Clan Akkaba appearances: New Excalibur #9
Powers: vaporized chest cavity filled with a fluctuating energy field that he manipulates through psionic biokinesis, enabling him to communicate telepathically through broad or personal thought projection and discharge volatile bolts of psionic energy
NOTE: After M-Day, Jono was depowered and then revitalized by the blood of Apocalypse, granting him physical features similar to Apocalypse and unrealized Omega potential. During this period, he wore a neck brace which gave him the power of sonic telekinesis, enabling him to fly, project ear-splitting shrieks, generate concussive force bolts and simple or complicated force field constructs. After Legion's Age of X reality warp, he appears to have been restored to his original physical state and mutant powers.
Genocide
First appearance: Uncanny X-Force #13
All Clan Akkaba appearances: Uncanny X-Force #13-17
Powers: living atomic furnace capable of producing radioactive heat blasts, exo-armor provides superhuman strength and resistance to injury
Genesis
First appearance: Uncanny X-Force #7
All Clan Akkaba appearances: none
Powers: superhuman strength, durability, shape-shifting abilities, dematerializer optic blasts, flight suit
NOTE: Other members of the modern Clan Akkaba have been shown but not named.
Alternate Timelines
Additionally, there's not only Apocalypse's descendants in the main reality to consider, as he fathered offspring in numerous other realities as well. In the Askani future, around the year 3680, Apocalypse’s daughter Diamanda Nero acted as his High Councilor and Viceroy. In that function, she led Apocalypse's empire during his hibernation phases. Diamanda had the ability to drain the life force and gain the powers of mutants she killed. Eventually, she faced a time-traveling Rachel Summers shortly after her arrival in that reality, where she was about to start the Askani movement. Diamanda wanted to add Rachel's powers to her own, but she was left defeated and powerless after being briefly bonded to the Phoenix Force. [X-Men Phoenix #1-3]
In the Age of Apocalypse timeline, Apocalypse was known to have at least one son originally called Nemesis, who dutifully served his father. On his first mission for his father, Nemesis killed the Scarlet Witch, earning him the wrath of her father, Magneto, who later destroyed his body in return. [X-Men Chronicles #1] Nemesis was saved from dying after being placed into a containment suit. Eventually, he became one of his father’s Horsemen and renamed himself Holocaust. While fighting the X-Men, Holocaust was impaled with a shard of the M’Kraan crystal by Nate Grey and was accidentally transported to Earth 616. [X-Men Omega] Later on, Holocaust was forced to the join the reality-jumping Exiles against his will. His time with the team was brief as shortly after joining the group, Holocaust died when one of the Exiles' archenemies, an evil Hyperion, cracked his containment suit and absorbed his entire life-force. [Exiles (1st series) #60-62] It is not known who Nemesis' mother was, nor if he has a counterpart in the 616 reality.
Armageddon is Apocalypse's son from yet another reality, one dubbed “Professor W’s X-Men.” He was created artificially using the genetic material of Apocalypse and Jean Grey. Using DNA harvested moments after Jean’s death, he was born to be his father’s ultimate weapon. However, Armageddon did not share his father’s views and openly opposed him, siding with the X-Men instead. Armageddon inherited his father’s strength and basic appearance, though he also possessed some of his mother’s abilities.
Nero, DiamandaFirst appearance: X-Men: Phoenix #1
All Clan Akkaba appearances: none
Powers: depowered mutant - previously possessed the power to permanently adapt the abilities of others at the moment of their death; demonstrated many assumed powers including superhuman speed, an indestructible exoskeleton, poisoned finger claws, telepathic immunity, lycanthropy, and the power to harness lightning
Note: It's not entirely clear if it was the writer's original intention for Nero to be Apocalypse's offspring as she was not referenced as such in X-Men: Phoenix 1-3. It wasn't until Official Handbook of the Marvel Universe: Alternate Universes 2005 that she was specifically referred to as his child.
Nemesis / Holocaust
First appearance: X-Men Alpha
Last appearance: Exiles (1st series) #62 [drained by Hyperion]
All Clan Akkaba appearances: none
Powers: crystalline armor sustains his energy form and grants him superhuman strength, nigh-impervious exo-structure, can project bio-genetic microwave blasts and drain the life-energy from other living beings, reducing them to ash
Armageddon
First appearance: Exiles (1st series) #41
All Clan Akkaba appearances: none
Powers: artificially engineered mutant possessing superhuman strength, endurance, resistance to physical injury, and intense telekinetic abilities