A robot was a mechanical being used by King Nub which came to life to kill any intruder who entered his tomb. Examples of robots were also present within the Infernal Machine in Babylon.
Some moved around by levitation and could cut people down with sharp spinning blades. Others were slower, lumbering robots that had scissor-like blades as weapons. There was yet another type that fired an electrical blast of energy.
Nub, a one-time priest of ancient Babylon, was able to harness a mixture of electricity and mechanical engineering to operate the robots which continued functioning even up until their discovery by Indiana Jones in 1947.
As dangerous as the smaller protectors were, a much larger guardian of Nub's crypt was accidentally activated by inserting a polished ruby into its mechanical eye socket. The giant robot attacked Jones by shooting a laser-like beam out of its gemstone and its clawed hands.
Jones used Nub's Part of the Infernal Machine to activate some energy plates within the floor of the tomb then lured the robot onto them. Electrocuted each time the robot made contact with a plate, its ruby eye eventually overheated and the guardian's functions shut down entirely.