Underlord Marcus is a rival Underlord in War for the Overworld. He appears in Campaign mode and as an AI personality in Skirmish and Multiplayer modes. He can also be seen as a contender in the Undergames.
In Campaign mode, Marcus is a cowardly traitor who flees from his realm into Kairos, and makes a deal with the Empire for his own protection. In exchange for this, he guards the third Inhibitor, preventing Oberon from progressing into the mainland of Kairos.
Mendichaus expresses great distaste for Marcus, and his behavior, and urges Oberon to eliminate him for his betrayal. He is eliminated, along with the third Inhibitor, in Level 4 of the Campaign.
In Campaign mode, Marcus does not make any effort to expand, alter, or repair his dungeon, and it appears that he has had a fair bit of time here to prepare already. He is meant more as a training AI for other Underlords later on rather than an actual opponent. When an assault is made against him, he will rally all troops to the first threat he sees, leaving other routes wide open. He will occasionally use lightning, though not very effectively, and he does not heal his minions often. He makes little effort to engage the player when not in immediate danger, and his workers do not usually stray far from home.
"Look how easily they throw their lives away, blindly following you to destruction... are you any different?"
"Withdraw your minions immediately!"
"There is only death for us here"
"Retreat from this place, we have no need to fight one another"
"I'll not kill my own kind, but you and your minions will not be the death of me"
"Please... let me be and leave this realm..."
"Leave this place!"
"You would kill your own kind for him?!"
"I can taste death fast approaching..."
"The Aether beckons, can you feel it tugging as I do?"
"You'll regret not heeding my advice. Underlord, this campaign will be the end of you"
- Marcus's dungeon theme in Campaign mode is the Sovereign theme. It is unlocked by players who purchase the game's Underlord Edition.
- His colour in the campaign is Cyan.
- He is a contender in the Undergames on the Blue bracket. He is eliminated before the final round.