A skullmonkey who helped Klaymen stop Evil Engine Number Nine. He gave Klaymen a root, which he used to put into the engine's exhaust pipe. Jerry-O was the only skullmonkey who seemed intelligent, this may be attributed to the device on his head. He was able to bring Klaymen with a sort of space suit. He may have invented it. Klogg did not fool Jerry-O, as he did the others.