"Silence, Simon!"

– Mr. Mogul

Simon is Mr. Mogul's assistant of the Rainbow Monkey, Inc.. He seems to accompany Mr. Mogul wherever he goes, and Mr. Mogul tells Simon to undergo silence whenever they laugh evilly. His first and only major appearance was in Operation: R.A.I.N.B.O.W.S., accompanying Mr. Mogul as they tricked Numbuh 3 into leading them to Rainbow Monkey Island. He later made cameos in various other episodes, mostly during villain meetings.