Brutus

Brutus is the armored prison guard of Mob of the Dead — a club-swinging bulk in riot gear who announces himself with a cell-door clang and a Romero-style roar, and whose real weapon is economics. As he stalks Alcatraz he slams locks onto whatever he passes: perk machines, workbenches, the Mystery Box, even the escape plane. Each unlock costs 2,000 points, and every re-lock that round doubles down another 2,000.

Fighting him

Body shots pay nothing — the fight runs through his helmet. Shooting it off pays 250 points and exposes his head, but also prompts him to pop smoke, blinding the area for long seconds while he closes in. He shrugs off Insta-Kill, breaks the Zombie Shield in one hit, disables the acid and fan traps rather than dying to them — the Tower Trap is the one machine that beats him — and on the Golden Gate Bridge he arrives with friends, up to four at once.

Who he is

He is the Warden of Alcatraz — never named in canon — who heard the Apothicons’ voices, rebuilt the prison as a corrupted temple, executed the four mobsters whose cycle the map replays, and electrocuted himself to rule the pocket dimension he had made. Sal speculates in-game that the guard is Stanley Ferguson, but Blood of the Dead establishes the zombified-guard form as a disguise; in that sequel the same entity, now simply "the Warden", is the antagonist outright, and his first kill drops the key the whole map turns on.