Zorak is a giant preying mantis (or quite possibly a locust). He is green and sports a blue vest; however, due to animation restraints, Zorak's color scheme changes throughout the course of a single episode.
In Space Ghost Coast to Coast, Space Ghost captured two of his former enemies Zorak and Moltar and forced them into doing the show with him. Consequently, Zorak is often trying to find ways to annoy Space Ghost (and quite possibly be freed from the show). He often interrupts the show to say things like "I am the lone locust of the apocalypse," but Space Ghost would occasionally shoots Zorak with his laser wrists. He never seems to see eye to eye with Space Ghost.
Cameo in the Film
During his cameo in the film, Zorak does not have any lines. Space Ghost says he is "smelling a missile," then turns to Zorak. Zorak stares at him, but Space Ghost decides that he is just imagining things. The Missile then comes through the window behind Space Ghost, and presumably kills both of them.