Revenants take many different forms in video games, though typically they are depicted as some sort of undead skeletal warrior. In games that feature skeletons, the Revenant is sometimes the more powerful version of the basic skeleton warrior.
In Revenant, it is depicted as a standard human who has been raised from the dead, and acts as normally as any other character.
In the Doom series, the Revenant is a skeleton with a rocket launcher on his shoulder, and a mean right hook when he gets up close and personal. From a distance, he fires slow-guided projectiles that are easy to outrun, but always hit on target.