Which key characters are most prominently featured during the events of the "Invincible War" arc?

The "Invincible War" arc prominently features Mark Grayson (Invincible) as the central protagonist, battling countless evil versions of himself. Other key characters include Atom Eve, Omni-Man (Nolan Grayson), Robot, the Guardians of the Globe, and members of the Coalition of Planets like Allen the Alien, who all join the desperate fight to defend Earth. Angstrom Levy is the primary orchestrator and antagonist, whose actions drive the entire conflict.