Zombo - Shut the appropriate door to prevent him if you see him in one of the hallways.
Clown - If he gets inside the office, Don't interact with the camera or buttons until he leaves. (Doors can stop him also)
Eyeless - Tap on it.
Pumpbie - Flash at him frequently to stop him from moving.
Herobrine - He'll go around the map until he's in your office, Watch him to not make him move.