REX-1 is a character who appears in two episodes of the Teenage Mutant Ninja Turtles (1987 animated series). He is a robot policeman and his name is an acronym for "Robot Enforcement Experiment," the "1" designating his status as the first model produced. His first appearance is in the second season episode, "New York's Shiniest". His only other appearance is in "Leonardo, the Renaissance Turtle".
Created as an experiment to relieve some of the burdens on New York City's human police department, REX-1 was prematurely activated by April O'Neil. Designed to be unwaveringly loyal to the operator of his remote control, he immediately considered April his master and would not leave her side. His designs were stolen by Shredder so he could mass-produce an army of robot cops under his own command. The Shredder robots were able to fire on some concrete, which rained down and rendered REX-1 inoperable. Donatello made repairs, but noticed his magnetic programming was ruined and replaced it with the closest thing the Turtles owned: old VHS tapes. With some help from April and the Ninja Turtles, the robot battalion was flushed out. However, Donatello's repairs had gone haywire, as REX-1 quoted lines from The Wizard of Oz, then opened fire on one evil robot while quoting John Wayne, then managed to get the remaining robots to destroy themselves by going haywire when he played an exercise video. Shredder noticed this from afar and expressed anger that his plans were foiled again. Afterwards, REX-1 had become more human, now leaving April alone but was on hand in case of emergency. He was last seen with Irma, saying his new mission is "to protect and serve, and take Irma to the movies!"
Sometime before his second appearance, he was placed back into storage at a police warehouse. April and Leonardo reactivated him in order to help stop a rogue robot named LEX, who sought to enslave the city with totalitarian justice.