Mortimer Mouse is a large mickey suit with empty eye sockets and is a prototype. He has the standard Mickey colors but has a darkened face, missing his right ear and right hand.
Mortimer will start crouching in the cabinet (1st phase) and will start moving during 1 A.M..
He has 5 phases. His 2nd phase is him in the cabinet slightly opened with his hand opening it.
The 3rd phase is when you can see the cabinet fully opened and his head is poking out.
At this point, he is a threat, and should be taken care of if any others are less of a threat.
His 4th phase is moving out of the cabinet with half of his body visible. now, he should be taken care of if nobody else is extremely close.
His 5th phase is fully out of the cabinet and staring at the camera. now, he is a major threat. No matter what, the player must immediately run out of the room and flash the cabinet. After 30 seconds, when he is in this phase and not flashed, Mortimer will run out of the room.
Now, death is inevitable. when he is flashed, he goes to phase 2. it is impossible to get him in phase 1 after he has moved out of that phase. he gets more active each night.
- In the "PLAY THE MUSIC" Mini-game, Mortimer must play music in front of a crying kid. pressing the button will make it louder and louder until Mortimer drops the microphone and devours the child before the Mini-game ends.
- He also appears in the "Salvage the dude". In the mini-game, Mortimer must disconnect Unfinished Goofy's wires and connect them to the wrong places, and then take his pieces apart. after this is done, Mortimer is shown smashing Unfinished Goofy's animatronic skull, and then devouring it.
- Mortimer will not move on night 11 at all. this is likely a bug.
- if the player hides under the desk when he is active, it slows him down, and it is possible to win the night when he is out of the cabinet.
- Sometimes, when he jumpscares you, the game freezes. the audio still remains and the night will finish itself. this is also likely a bug.
- He and Steam Boat Willy are closely related.
- He is the only character to not become deceased, as he is the cause of said death of other characters, not counting AAAAAAAA, who is a hallucination.