Marcus is a character who first appears in Ash vs Evil Dead Season Three. Marcus is part of the Knights of Sumeria, a secretive organization sworn to protect mankind from all evil. He is a member of a group led by Zoe in search for their friend and fellow member, Dalton.
Marcus made his debut in Ash vs Evil Dead episode Tales From The Rift. Alongside his fellow knights Zoe, Peter and an unnamed forth guy joined forces with Ash and Pablo. They were searching for Dalton and eventually Ash, whom they believe is the savior of mankind. After a brief chat with Ash at his home the four knights sworn themselves to protect him.
The five of them went back to Brock's general store where a portal to other dimensions was hidden. Marcus told Ash that the rift should teleport them to the land of the dead where they can have a battle against evil at their own territory. It was to be an eternal battle and Ash wasn't too keen on the idea to go in head first.
In order to prove to Ash that the passageway was safe Marcus volunteered to be the first to use it. He successfully crossed realms, but a few moments later he came back seemingly unharmed.
The momentary calmness turned into a bloodbath when Marcus turned out to be infected. He attacked Peter and merged his comrade's body into his own becoming a two headed demonic entity in the process.
Soon after, he ripped off the head of the other unnamed knight's head off, thus leaving Zoe the only one alive from their group.
The possessed Marcus was then finished off by Ash with the help of Zoe and Pablo.