William “Billy” Hensen was a Cybertek scientist who developed the Deathlok and Warwolf projects. He was also Harlan Ryker’s best friend.
When John Kelly, Cybertek’s first attempt at Deathlok malfunctioned and Cybertek had to dispose of his brain, Hansen kept the brain for further study. Hansen planned to experiment with the nanofluid that preserves Deathlok’s organics, and see if it could be used to resuscitate Kelly. When his experiments seemed to fail, Hansen disposed of the brain.
When Nick Fury shut down Cybertek and Ryker went on trial, Hansen was one of the first people Ryker had Warwolf kill to destroy evidence.
Death was not the end for Billy Hansen, however. Unbeknownst to Hansen his experiments with Kelly had in fact worked, albeit over a much longer period than he had expected. Kelly’s brain had mutated into the horrifying creature known as Biohazard, which was desperate to make sense of its existence. Biohazard ate Hansen’s brain and created a genetic clone of Hansen.
Alive once more, Hansen was compelled to go to Michael Collins and share his macabre story. He explained that Biohazard, having now absorbed his knowledge, knew that there was an uncorrupted set of his memories preserved within Collins’s Deathlok operating system. In order to regain full functionality, all Biohazard needed to do was eat Michael’s brain, and be able to reconstruct Kelly’s full consciousness.
Hansen then realized he didn’t know why he himself had been revived, just before he was violently transformed into Biohazard, who had used Hansen as a biological Trojan horse to attack Deathlok. Once more Hansen’s mind was wiped away, leaving only Kelly.