There are many different versions of Brian Braddock across the multiverse. What’s unusual is that many of those Brians are also members of the Captain Britain Corps (though not automatically every Captain is a Brian Braddock) and therefore there is a high chance that those Brians keep on bumping into each other.
The first alternate Braddock Captain Britain encountered was Captain England, a bearded counterpart who spoke in a broad Yorkshire dialect and, in addition to the usual Captain Britain powers, also had a staff capable of creating extreme cold. Captain England is from an Earth that’s called “the Hub”, it’s the reality where the court of Saturnyne's trial was set. In fact, the two Captains fought over the fate of Saturnyne. Captain England seemed to be a good sport, though, and later introduced Captain Britain to several other members of the Captain Britain Corps.
On Earth 839 Byron Bradhok was the lover of Sat-yr-9, the sadistic despotic ruler of that reality’s Great Britain. While his position allowed him to satisfy his own sadistic urges, his servitude nevertheless chafed. During Merlyn’s funeral, he saw the naive Captain Britain and from then on tried to have the other man attacked. Eventually, he took Braddock’s place while an unsuspecting Technet brought the real Brian Braddock to Sat-yr-9. Kaptain Briton picked up his counterpart’s life and even went as far as trying to rape Betsy Braddock, who then used her burgeoning psychic powers to kill him.
In a world where the Nazis had won World War II, Earth 597, Brian Braddock aka Hauptmann Englande was serving as the leader of Lightning Squad, this world’s version of Excalibur. Being a perfect Nazi, Hauptmann Englande was cruel, cold and remorseless. When the Lightning Squad crossed over to Earth 616 in search of their world’s version of Moira MacTaggert and fought Excalibur, Hauptmann Englande had a special dislike for Captain Britain. He also acted as a prosecutor when Captain Britain was put on trial in front of the Captain Britain Corps. Much later, he was killed defending Otherworld from Mastermind.
In the world shown in Excalibur (1st series) #21-22, Great Britain was still a powerful empire and the American colonies had never won their independence. Captain Britain’s counterpart was named Bran Braddock and he was apparently an Indian, suffering from racism in his civilian identity. As Crusader X, he was the Empire’s foremost hero, closely working with the X-Men, the secret service headed by Charles Xavier. He also had a relationship with his world’s version of Courtney Ross, who strangely enough looked like Kitty Pryde. When Mastermind impersonated Roma and destroyed a great part of the Captain Britain Corps, Crusader X was one of the few members still around a fighting. By then it was, however, a Caucasian, blond Crusader. It is unclear whether he had somehow changed his appearance, or if this was supposed to be a new Crusader X.
Another Earth, depicted in Excalibur (1st series) #23 was almost destroyed by a war between its superbeings until Brian Braddock set himself up as Lord High Justicer of a new police force (with his sister Psylocke acting as Examining Magistrate) that outlawed all kinds of superhuman activity. Interestingly enough, it is not he who appears to be this world’s member of the Captain Britain Corps (despite having the power), but Justicer Bull, one of his Justicers.
There were numerous other versions of Captain Britain (and Excalibur) that were introduced either during the Cross-Time Caper or popped up near the main universe Excalibur’s lighthouse, as it was a nexus place. Most of them were unrecognizable and seemed to be based on sentient animal life forms rather than humans. The Captain of a world where dinosaurs never became extinct and instead developed sentience referred to himself as “Britanicus Rex” and was the leader of his world’s version of Excalibur.
The early death of Charles Xavier created an alternate timeline, the Age of Apocalypse, in which En Sabah Nur rose to power. Brian Braddock never received superpowers or became Captain Britain. He was a gung-ho member of the European Human High Council and, along with Moira and Bolivar Trask, Mariko Yashida and the lobotomized Emma Frost, he led the Council in their efforts to provide safe haven to those humans who had escaped from Apocalypse’s territories. Eventually. though, Brian betrayed the rest of the Council by siding with Donald Pierce. In the last instant, Brian tried to rectify his error, but was shot by Pierce before he could do any harm to the cyborg’s plans.
In a possible future not unlike the Days of Future Past timeline, Brian was married to Meggan, and still served Excalibur, a now outlawed team led by Pete Wisdom. While in the United States, the X-Men were already killed or captured by the Sentinels, Great Britain faced problems of their own. The last mission Excalibur went on was to save Douglock from Black Air, the evil, secret organization that had taken over the country, but the team found themselves lured into a trap – as Douglock had become Black Air’s major weapon. Apparently, all of the team, including the Braddocks, were killed.
Ten to fifteen years ahead, in the timeline called Earth X, Captain Britain became monarch of all of Europe, wielding both the Amulet of Right and the Sword of Might. His team Excalibur, including his wife Meggan, were turned to stone by the Grey Gargoyle and King Britain has been fearful of trying to save them with his magical sword, not entirely sure what effects it might have on them. After the Inhumans Royal family left Earth, Brian took in and raised the Inhumans’ crown prince. Later, after the Inhumans‘ return, Captain Britain wed Medusa, Queen of the Inhumans, in a political move. However, some time later, Meggan was returned to him. Unfortunately, Brian found that he could not break up the union with Medusa, and Meggan had to leave. She still loved Brian, though, as she eventually sacrificed her life to save him from Mephisto, whom Brian then slew.
In the Ultimate universe, Brian Braddock is the son of Professor James Braddock and brother to the telepathic STRIKE agent Betsy Braddock. Along with his father, Brian worked at the European Defense council, a European answer to the American supersoldier program. Great Britain, as well as several other member states, developed suits capable of giving their wearers superpowers. Using the armor, Brian has decided to call himself Captain Britain. So far, the European heroes have teamed up with the Ultimates several times.