Xa-Du was a Kryptonian researcher, interested in improving research into suspended animation. However, the unethical nature of his studies led to the Kryptonian Science Council suspending his research and choosing him as the first inmate of the Phantom Zone. A sociopath, Xa-Du swore revenge on the family of the Phantom Zones discoverer, Jor-El.

Over the course of his incarceration in the Phantom Zone, Xa-Du built an ecto-suit to allow him to walk free. However, Krypton exploded before it was complete, and his one attempt at revenge was thwarted by Krypto, the Els dog.