Osiris

Osiris  will be mentioned as an "Anti-" by Thanos.

He was once one of Thanos’ Escorts, but was exiled from Clockhaven for insubordination & homicide.

Thanos recounted Osiris’ story as “a rebellious Senghi found guilty of multiple assassinations of younger apprentices, exiled as an Anti-Time Astral.” He isn’t the friendliest of Anti’s, especially if someone approaches him and has relations to Thanos.

Osiris resides in Grimhaven, a station city outside the three original space stations (Clockhaven, Emberguard & Aquarin). Not much is known about his personality or intentions in the present-day; You’d have to run into him to find out.

Trivia

 * Aside from Apep, and SharaX with no bio, Osiris seems to be the most vague character in the Undertronic series.
 * Since Apep and Osiris are good friends it's possible that Apep is the only one that knows anything about him.