Sylvester McMonkey McBean is a character in The Sneetches and Other Stories book and a segment in the 1973 cartoon short Dr. Seuss on the Loose, where he is voiced by Bob Holt. A yellow earless monkey who happens to be a "fix-it-up chappie," McBean appears and offers the Sneetches without stars the chance to have them with his Green Star-On Machine, for three dollars. The treatment is instantly popular, but this upsets the original star-bellied Sneetches, as they are in danger of losing their special status. McBean then tells them about his Star-Off machine, costing ten dollars, and the Sneetches who originally had stars happily pay the money to have them removed in order to remain special. However, McBean does not share the prejudices of the Sneetches, and allows the recently starred Sneetches through this machine as well. Ultimately this escalates, with the Sneetches running from one machine to the next.
This continues until the Sneetches are broke and McBean departs a rich man, amused by their folly, and says to the audience "you can't teach a Sneetch". The narrator then comments that ultimately McBean was wrong, for the Sneeches soon learn that star bellies nor lack of stars cause inferior nor superior status, and they soon all live on the beach as one group.
In the book he wears a green hat and a green bowtie, but in the video he is more humanistic in appearance, wearing a purple hat and a lavender pink bowtie and a green jumpsuit. In the book he has ears but in the video he has yellow hair.