The atomic steeds were original developed by the High Evolutionary to be ridden by the Knights of Wundagore. During a battle between the Avengers and Cthon, the mutant hero Beast happened upon the skeletal remains of one of the Knights of Wundagore, and soon found its atomic steed buried in the snow. Using the deceased knight's armor and steed, Beast was able to help the Avengers defeat the elder god Cthon. The Avengers brought the steed back with them to Avengers Mansion, where the device was placed in storage for quite a while. Some time later, it was eventually found by Black Knight, who used it during the team's battle with Nebula. Black Knight would continue to use the atomic steed for many years, using it as a replacement for Aragorn, his winged horse.
After Black Knight left the team so that he and Sersi could travel to the Ultraverse, the atomic steed fell into disuse. It was eventually rendered obsolete entirely when the Black Knight returned to the mainstream Marvel Universe, and was given a new flying horse by the name of Strider. Despite this, the atomic steed was taken out of storage to be used by the new Swordsman, who'd allied himself with the Avengers during Black Knight's absence. Hawkeye later brought the steed out of storage once more as part of his plan to impersonate Dreadknight. He would continue to use the vehicle during his tenure as the leader of the Thunderbolts. Years later, Black Knight briefly used his atomic steed once more, only for it to be destroyed by Inferno of the Exemplars.
In Other Media
- The Marvel Legends Hawkeye figure from ToyBiz came packaged with the Black Knight's Atomic Steed as an accessory and a display stand, mirroring Hawkeye's use of the vehicle in the comics at the time.