Marcus
"The Guardian"
During the War for the Overworld campaign, Marcus has betrayed the evil god Mendechaus, and is helping the Empire. As such, he is an opponent to the player.
The Under Games campaign, which takes place a long time before the main War for the Overworld campaign, has Marcus appearing as an opponent to the player.
Marcus is also an AI personality for Skirmish and Multiplayer games.
Dialogue during the Under Games indicate that Marcus is reluctant to wage war. This attitude is likely what lead to him betraying Mendechaus later.
Theme: Sovereign
This theme is unlocked by owning the Underlord Edition of the game.
Color: Cyan
Marcus always appears with the Cyan color during campaigns.