The Master Cylinder was an evil robot that appeared as a major antagonist in the 1960 Felix the Cat cartoon "Master Cylinder - Master of the Moon" (where he calls himself "King of the Moon") and he first appeared in Joe Oriolo's 1959 revival of Felix the Cat, he would then proceed to become one of Felix's main enemies throughout the series: unlike the Professor, Master Cylinder was never helpful nor friendly to Felix in any of his appearances and remained villainous (while The Professor often switched between the role of an antagonist and an uneasy ally). In his first appearance, he was defeated by being unplugged. He overcame this weakness by gaining feet and operating with a different power source. He can extend his arms, fly, and shoot lazers from the yellow rectangle on his forehead.
The robot gained its name from its shape (which resembled a cylinder) and was given an origin in Felix the Cat: The Movie in which it was revealed that Master Cylinder was a creation of the Duke of Zill and the most powerful of the Cylinder robots and thus was the general over them - Master Cylinder would proceed to make a brief appearance in the movie when The Duke unleashed an updated version of the robot in an effort to destroy the heroes. Poindexter's "glitchomatic" (the red button on his shirt) can cause him to malfunction for about 20 seconds.
However Felix acted quickly and threw a magic tome known as the Book of Oriana which saved Felix and his friends, at Master Cylinder, causing the robot to explode and seemingly destroying his old enemy once and for all.
It is revealed here that Mater Cylinder was a creation of the Duke of Zill and was released toward the end of the movie to destroy Felix and friends. He had machine guns, lasers, and a flam thrower. He had all kinds of gages on his face. He had sharper claws too. All the cylinders redirected their power from him so when Felix exploded him, the cylinders were destroyed too.
- He was voiced by Jack Mercer, and later John Stocker.
- In his debut episode, Master Cylinder describes himself as a disembodied brain contained within an electromechanical body.
- The Master Cylinder had a minion, to be seen in later episodes, and that minion is a helmeted white squid named General Clang.
- Master Cylinder also had another minion, Rock Bottom, but this was only on occasion.