An employee at Belko Industries.
- Nice Guy: Mike gets along with pretty much everyone.
- Thou Shall Not Kill: Tries all film to avoid killing. Only when Leandra is killed does he give up, and goes for Barry.
- Took a Level in Badass: Originally against killing he goes from an average office worker to someone who beats his boss to death with a tape dispenser and massacres the heads of the experiments with their own bombs and an assault rifle.
- Sole Survivor: The winner, as it were, as the last surviving employee.
The COO of Belko.
- The Heavy: Though The Voice is the true villain, Barry is the prominent threat in the building.
- Jumping Off the Slippery Slope: He tries to be rational in the beginning. But when it becomes apparent it's them or him, he assumes role of Judge, Jury, and Executioner.
- Reasonable Authority Figure: Being the COO and the one that many look to in the beginning of the experiment, he starts off like this, before gradually Jumping Off the Slippery Slope.
- Retired Badass: Someone comment he is ex special forces and he does have the skill to match it.
A socially awkward top executive.
- Asshole Victim: Being an Ax-Crazy, sexual harasser who ruthlessly starts murdering other employees with no remorse when the experiment really kicks off, no one mourns him.
- Ax-Crazy: Wendell is the quickest to acclimate to the game, and clearly didn't have far to fall mentally.
- The Brute: Serves as Barry's unstable muscle during stage 2.
- No Social Skills: Wendell seems lacking in any social intelligence, and believes "Fuck off" counts as a "Mixed signal" from Leandra.
- Stalker with a Crush: He stares incessantly at Leandra.
A new hire at Belko.
Belko's head of Maintenance.
- Dead Star Walking: Dies from a wrench to the head early on.
Alonso "Lonny" Crane
- Sanity Slippage: The first employee who truly starts cracking under the pressure. And first to kill another employee, if accidentally.
The voice providing the instructions of the Deadly game to the workers.
- Big Bad: The primary antagonist and the reason for all the hell breaking loose.
- Entitled Bastard: Oh, so much!
- Hoist by His Own Petard: He forces Mike to give up his Thou Shalt Not Kill stance during the climax, which comes back to bite him in the ass when Mike has him cornered. He even has the gall to make a Call-Back to that trope in a pathetic attempt to save his own life. It doesn't work.
- Laser-Guided Karma: Dies a well-deserved death at the hands of Mike.
- Smug Snake: Thinks he has complete control over everything, to the point of having Mike brought to him after all the other employees have been killed so he can interview him on how the killings affected Mike's psyche - without making sure that Mike was unarmed first! BIG mistake.
- Villains Want Mercy: Has the nerve to beg for his life when Mike is holding him at gunpoint.