Otis Washington

An elderly mall janitor. Otis tries in vain to stop Frank from pursuing Brad back into the mall, and eventually concedes and bestows upon Frank a spare transceiver and an intricately detailed map of the entire mall. He sporadically sends the player information and the location of survivors via Frank's receiver. If Frank is unable to reach the stairs of the Entrance Plaza when the zombies first breach the barricade, and in lieu of escaping is knocked out, Otis carries Frank to the safety of the security room. Once it is apparent that the survivors have completely dispersed, he welds the main entrance to the security room shut to prevent zombie intrusion. When the Special Forces arrive, Otis sneaks out, surreptitiously acquires a military helicopter, and flies himself and the survivors that Frank rescued to safety.

Infinity Mode
Otis is the first enemy encountered in Infinity Mode. He is fought atop the mall's roof, wielding a frying pan.

Trivia

 * Despite being one of the most talkative characters in the entire game, Otis' voice is never actually heard, except when he screams when killed in Infinity Mode.
 * Otis appears to find the situation "fun", and says to Frank that he can't sleep with excitement. None the less, he barely has anything to do with the situation, and stays in the security room all day.
 * How he managed to fit every single survivor into one helicopter is unknown, he may have flown one group away from the town and then turned back to pick up the remaining ones.
 * He stays in the security room but knows about survivor locations and such more than Frank, due to being able to watch the monitors constantly
 * Otis is notorious for being one of characters players hate the most, due to his tendency to call Frank while he is in the middle of a battle. Many players take great joy in killing Otis in Infinity Mode.
 * There is a weapon glitch involving Otis' calls. When Otis is calling you, make sure you have a semi-automatic gun, such as the Real Mega Buster one inventory slot away from your current weapon. Answer the call, then switch to that weapon. Make sure that when you answer the call and switch weapons you are running. When you hold down the fire button, your weapon will fire as fast as a Machine Gun You have to stay running or the glitch will stop.