Marcel was Ross's pet white-headed capuchin monkey (Cebus capucinus), during season 1. He also made other appearances and was mentioned later on. He has a fondness for the song "The Lion Sleeps Tonight".

In "The One With The Monkey", Ross shows up to Monica's New Year's Eve party with Marcel as his date. On one occasion in "The One Where The Monkey Gets Away", Rachel has to look after Marcel and while watching a soap together he runs off. She quickly reports him missing, much to the fury of Ross, as Marcel is an illegal exotic animal. The group sets out to find the monkey before the authorities do. The woman searching for him turns out to be a classmate of Rachel and Monica, but they didn't treat her too well.Phoebe then finds Marcel, at the same time as the woman. Phoebe jumps in the line of the tranquilizer dart which is aimed at Marcel. Rachel then uses this as blackmail to allow Marcel free.

In "The One With The Fake Monica", Marcel reached sexual maturity and started humping everything, and Ross learned that he would soon have to give the monkey away to a zoo. After an interview with Dr. Baldharan, a man who owned an animal fighting ring, Ross was relieved when Joey and Chandler informed him that Marcel had been accepted by San Diego Zoo.

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