Darius Dax, full name Darius Christian Dax (1916 - 1968) was the arch-enemy of Supreme. An evil genius, his scientific terrors challenged the hero from his time as Kid Supreme through the 1960s. Raised in Littlehaven, Dax had been jealous since adolescence of Kid Supreme's power, which overshadowed even his own massive intellect. Dax's schemes led him to ally at times with other villains like Jack-a-Dandy, enemy of Professor Night, and the time-travelling League of Infamy.
However, Dax's misdeeds caught up with him, as he discovered in 1967 that his exposure to supremium as a teenager caused him to contract lymphatic cancer. With about a year to live, he transferred his memories into thousands of tiny computers- smart dust- and encoded them into a book, given as a gift to Judy Jordan. When Jordan read the book, the smart dust erased Judy's personality and memories and installed Dax's own over the course of a week.
At the time, Supreme had disappeared into space, so Dax/Judy waited years for Supreme to return, building the android Hilda and pretending to carry Jordan's life forward in the meantime. When Supreme returned in the 1990s, Dax/Judy began his plan. Using Hilda, he infiltrated Supreme's Citadel Supreme, destroying its defending Suprematons and trapping Supreme himself in the Hell of Mirrors. Dax then used the Citadel to threaten Omegapolis, and transferred himself from Judy's aged body to that of the powerful android Magno. However, Hilda was destroyed by the Allies and despite Magno's power, Dax found himself outmatched. So, he absorbed Supreme's sample of violet supremium, transforming into the original Supremium Man. However, his supremium-laced self was drawn to the only other sample, which last existed in 1958 Littlehaven, and he disappeared back into time.
Like Supreme had been, he was rescued from oblivion by his deleted variant selves in Daxia, who transported his normalized self back to normal reality so that he could plot anew.
In an unpublished story, Dax would have led his Daxia-dwelling variants in an assault on Omegapolis and the Supremacy.