American television puppet character (and one of the Muppets), whose appetite for cookies is legendary. Together with such characters as Oscar the Grouch, Elmo, and Big Bird, he is one of the featured creatures on the long-running children's public television series Sesame Street.

The childlike Cookie Monster's daily life revolves around his namesake treat. When he is not eating cookies—chocolate chip being his favourite variety—he is demanding them, musing upon their surely mystical origin, or delivering spontaneous odes to their greatness. His signature song is "C Is for Cookie." When cookies are not available, his appetite allows virtually anything else, including normally inedible objects. His notable alter ego was Alistair Cookie, host of the recurring Sesame Street segment Monsterpiece Theater, a send-up of public television's noted Masterpiece Theater series and its host, Alistair Cooke (Cooke, Alistair).

The character of the furry, blue Cookie Monster developed gradually and informally, with input from Sesame Street creator Jim Henson (Henson, Jim) and several writers and puppeteers. Henson's longtime collaborator Frank Oz (byname of Richard Frank Oznowicz) performed the character's voice and movements for more than 30 years, beginning with his first Sesame Street appearance in 1969, and Oz is often credited as the greatest creative force in the character's genesis.

In 2005, as part of an effort to address the growing problem of childhood obesity in the United States, Sesame Street producers began to moderate the character's appetite for cookies. Thereafter, Cookie Monster professed to enjoying many healthy foods, such as fruits and vegetables, while still ferociously devouring cookies for dessert.