- "Warning, re-entry detected. All security personnel on high alert."
- — Ascension announcer at the beginning of a Space Monkey round
Space Monkeys are an enemy exclusive to the map Ascension. They occur every four to five rounds after a perk has been bought. They steal the players' perks in the form of attacking the various perk machines, and can also damage and kill the player. They replace Hellhounds and the Pentagon Thief. They wear space suits similar to the ones worn by regular zombies, and are likely zombified primates from the Soviet Space Program.
The Space Monkeys will attack a perk machine until the player loses their perk. Perk Machines have 100 HP and monkeys inflict one damage on the machine if players are far from the machine, and eight if the players are close up. Once the machine has been disabled, the player must re-buy the perk. The last Space Monkey, upon death, will drop a Max Ammo, and also a Random Perk Bottle if the players successfully kill all monkeys without having any machines damaged. It should be noted that if the player has obtained a perk from the Random Perk Bottle and have not opened the area in which the Perk-a-Cola is located, the Space Monkeys will not attack that perk machine. Monkeys have two different attacks: close range which is strong, and long range which will cause the player to become dazed and weakened, though if the player is in the air when the monkey uses this attack, they will be unaffected. They can also throw back grenades. Once a monkey has taken out a perk machine, any monkeys involved in breaking it do not appear to be able to break any other perk machines and will exclusively target players. If the player(s) then use any means to make themselves undetectable, through GobbleGum or other means, the monkeys will act like any other zombies and run to a random location, if a player walks near them in this state, they may still perform the slam attack, and damage the player.
When the monkey round occurs, the player will hear a buzzer in the beginning of the round, and the map will turn in a yellow-orange tint. Also, the announcer will warn the player by saying "Warning. Re-entry detected. All security personnel on high alert." The monkeys arrive in lunar landers crashing onto the ground. When the round finishes, the announcer will say "Security level normalized. System defenses offline."
It can be assumed that they are related in some way to Yuri Zavoyski due to an excerpt from his rant in the second radio message, "My intellect is ill served blasting a bunch of monkeys into the atmosphere!". It can also be assumed that they have been exposed to Element 115, due to their glowing red eyes and increased physical capabilities.
- When Space Monkeys die, they appear to release a red pulse. This pulse can damage perk machines.
- Monkey rounds will only occur after at least one player has purchased a perk. Because of this, they will not spawn until the power has been turned on. In Solo, if one has bought Quick Revive, they still will not arrive until the power is activated.
- The monkeys appear to be resistant to the effects of the Thundergun, as they simply perform a back-flip and continue to attack the player. A second well placed, consecutive shot should kill them.
- When a Gersh Device is used on a monkey, they willingly jump through it, but it will not kill them, only teleport them to a different area.
- Monkeys can destroy claymores without damaging themselves. However, monkeys cannot destroy a claymore if it is not level with them, so a claymore placed on a set of stairs can kill monkeys.
- On the left side of their space suits, one can see the Treyarch symbol.
- There is a magazine mentioning the Space Monkeys in multiple maps and missions.
- Even if the player has PHD Flopper, they can still take damage/go down when a monkey throws your grenades back at you.