The Doomsday Virus was a fatal virus emitted by the Doomsday creature. It killed anything within a certain radius of Doomsday, allowing it to absorb their life force. It did not affect Wonder Woman, who was immune due to her unique heritage. Steel was able to cure himself of it and avoid an early fatality due to his combat armour. On Superman, however, the virus was able to try and transform the Kryptonian into another Doomsday-like creature.