Killbots

A Killbot is a type of robot, which is programmed for one purpose: Killing. For unknown reasons, a kill limit of 999,999 was hardcoded into the killbots.

Zapp Brannigan once faced a horde of these killing machines. However, he defeated them by sacrificing waves of his own men, until the killbots' kill limit was reached. When the kill-limit is reached, killbots become rather friendly. However, their kill counter has the option of being reset, which reactivates their need to kill.

Additionally, Professor Farnsworth and Wernstrom have each designed at least one killbot.

They can never hear what anyone is saying because of the huge amount of killing they do.