- "Here it is! Wasn't so bad! It's only ever in one of two places!"
- — Albert Arlington when picking up the key.
The Warden's Key, also refereed to as the Master Key, is an obtainable part in Mob of the Dead. It is necessary to obtain all of the plane parts. It appears as a golden key with three holes, attached to a key chain.
The key can be located either above the Warden's Office or Cafeteria entrance. Electric sparks can be seen on the wire from which it is hanging. To obtain it, the player must enter Afterlife, jump through an Afterlife entrance high on the wall and shock the nearby electric panel, which will lower the key and disable the electricity surrounding it. The key can then be grabbed when out of Afterlife.
The key can open the following locks, all are used to obtain parts for Icarus:
- The elevator door in the citadel tunnels, for the rigging part.
- The door towards the washing machine, for the uniforms part.
- The door in the Warden's office, for the engine part.
- The door at the docks, for the tank part.
- The glass case near the roof's staircases, for the valves part.
- It is possible to see the key spawning in the Cafeteria entrance from the spawn, when looking through a narrow window on an unopenable door. Thus players can know where the key is located before leaving the spawn.
- The Warden's Key hanging above the player is a reference to how correction officers at Alcatraz would hang their keys from the Gun Gallery so they could be safely and quickly transferred between guards on the lower floors. It has the same appearance the key from Alcatraz 
- In the Mob of the Dead loading screen and intro, it is said that the Warden's key is the first step in the escape plan. In real life, a known escape attempt named "Battle of Alcatraz" started as one of the prisoners managed to put his hands on the Wardens' guns and keys as a part of his escape plan. The escape plan went successful until the prisoners headed to a doorway to docks and found out the lock on the door is jammed. Failing to use the key and get to the docks, the prisoners became trapped in the cellhouse, leading to the failure of the escape.
- Alcatraz Island audio tours