In his Tarkaetan form, he has purple skin, like all male tarkaetans, and bright blue eyes. In his human disguise he has black hair, light grey skin, and wears a black jacket over a purple shirt.
Atlas, like all Tarkaetans, has the ability to shapeshift into any known race in the universe, however he only uses this ability when invading a new planet.
Atlas is very by-the-book, only understanding and doing things as he's told to do. He isn't a push-over, but he follows his authorities because otherwise he doesn't know what to do or where to go.
Atlas and his older brother Varian grew up in the Tarkaetan society of shapeshifting aliens as the sons of the King, with Varian growing up to become the Prince of the Tarkaetans, destined to lead their race in the invasion on Earth. However, when Varian went to earth, he disappeared and was presumed dead. For a long time, the Tarkaetans didn't know that the former prince had taken up a new identity, becoming the human female Teresa.
Atlas was distraught after Teresa's supposed death and secretly hoped she was still alive, becoming the New Prince of The Tarkaetans. When The Tarkaetans finally found Teresa, Atlas was conflicted on how he should feel - happy that his brother was alive, but confused by her new identity and angered that she broke away. During the events of Invaders, he leads the Tarkaetans to capture Teresa and invade Earth, but Teresa, along with Cura, Ray, and Chelsea Rench, oppose his efforts.
Relationships with Other Characters
Atlas still cares deeply about Teresa, being the only one who still had hope that she was alive after her presumed death. But still, he doesn't understand why she broke away and changed her identity, refusing to call her by female pronouns.