ALTERNATE VERSIONS
In the Age of Apocalypse, Mikhail Rasputin never went on that fateful flight through the void. Instead, he established himself as one of Russia's greatest heroes alongside his brother Piotr 
before turning against humanity and becoming one of Apocalypse's Horsemen. Mikhail had a very different appearance in the Age of Apocalypse, either from turning his own powers on himself, or perhaps experiments performed by one of Apocalypse's gene scientists. Mikhail ruled directly over the northern Midwest region of what was once America in Apocalypse's name.
Although he had apparently been working for Apocalypse since before Colossus joined the original X-Men, Mikhail mostly worked behind the scenes in Apocalypse's empire, earning him the titles of the Invisible Horseman, or the Forgotten Horseman. He was chiefly responsible for the Upscale Program. Years earlier, Mikhail somehow came across young Matt Murdock shortly after the accident that took his sight and augmented his other senses. Mikhail had a cybernetic visor grafted onto the boy's face, and earned Murdock's loyalty by claiming his efforts were responsible for the boy's enhanced senses. Building on this success, Rasputin crafted an entire bio-augmention program to give bionic or genetic enhancements to flatscans willing to serve him...enhancements that functioned at the discretion of his own matter/energy manipulation powers, allowing him to control the Upscaled flatscans with a gesture, or remove their new abilities altogether.
During the Age, Mikhail led a "peace initiative" in Apocalypse's name to London, making contact with the beleagured Human High Council on humanitarian relief efforts. While bringing food and medical supplies as an olive branch to their human enemies, Mikhail also arranged to sabotage the Eurasian bombers and pilots who could potentially target Apocalypse Island. And, through the manipulations of the captive empath Manuel de le Rocha, Mikhail twisted the emotions of the starving Eurasian people to compel them into submitting to the Upscale Program. A small band of freedom fighters including Donald Blake, Tony Stark, and Gwen Stacy resisted Empath's influence and freed the human captives, sabotaging Mikhail's mother ship from the inside. Inside Big Ben's broken clock, Don Blake defended what was left of the High Council from Mikhail. The God of Thunder never regained his identity in the Age of Apocalypse, but Blake was still a hero at heart, and sacrificed himself by plunging his cane through Mikhail's heart and charging them both out of the clock tower to fall dead on the streets below.
In the Domain of Apocalypse on Battleworld, a version of Mikhail was briefly seen. However, he wasn't among the identified Horsemen dealing with Dr. Nemesis and the Legacy Virus scheme.
In the Ultimate Universe, Colossus had several younger siblings depicted back home. It's possible that Mikhail was Piotr's little brother on this world, or Piotr had some other brother who wasn't an analog to Mikhail.