Zakaius was an alien being of an undefined race that could easily pass as a human of Earth. The details of his early exploits and adventures are unknown, however, it was revealed that he was appointed to the Imperial Court of Domitian many years ago. At some point he was elevated to the position of Executioner to the Court. He would act as judge and jury of "sinners" that had been handed the Death Sentence by his master. He would drain them of their Life-Force and preserve it in a rune stone that he would deliver to his master that was able to utilize the stones essence to revitalize his own life. On the planet Luraei, Zakaius collected the life-force of the former herald of Galactus known as Firelord.
A short time later he was assigned to cast his death sentence on Adam Warlock and the Infinity Watch, which led him to Pittsburgh, Pennsylvania where he recruited a local biker gang via his powers of mental and emotional manipulation, to act as his minions. Warlock received a precognitive message from his Soul Gem revealing the imminent threat of Zakaius and his current location, which allowed Pip the Troll to teleport Warlock and the Infinity Watch to the biker bar where Zakaius was. The two sides got into a battle that resulted in Zakaius exploding a tanker truck by accident and Warlock and the Infinity instinctively began rescuing the innocent, which caused Zakaius to question his judgment of all those he had accused of being sinners, including Firelord.
Zakaius agreed to accompany the Infinity Watch back to the Imperial Court to confront Domitian. Once they arrived outside the palace, they were confronted by Kaef, and told that to question the will of Domitian constituted heresy, and he attacked them all. With the aid of the Infinity Watch, Domitian and his cyborg army was defeated and Firelord's Life-Force was returned to his body. Zakaius promised Warlock the he would return his other victims life-force as restitution for his own sins.