Beloved actor and comedian Robin Williams appeared as a guest star in an episode of Friends in 1997. Williams played a character named Tomas in the Friends season 3 episode, "The One With The Ultimate Fighting Champion", and considering how big of an actor Williams already was at the time, starring in the comedy series was a huge deal.
At the start of the episode, Monica was about to tell her friends a story at Central Perk but was interrupted by Tomas and his friend Tim, a character played by Billy Crystal. The men asked the group to make room on the sofa in which they obliged. They then eavesdropped as Tomas broke into tears claiming that his wife was sleeping with another man. Tomas believed the other man was her gynecologist but it turned out that Tim was the "other man". Joey tried to interrupt the conversation but was rudely told by Tim to mind his own business. Tomas ended his friendship with Tim before he stormed out of the coffee shop with an embarrassed Tim following behind. After they left, Monica completely forgot the story she was originally planning to tell.
Guest appearances by big names like Williams and Crystal weren't rare for Friends during its decade on air. It was common for popular actors to make guest spots. Brad Pitt, Julia Roberts, Bruce Willis, and Christina Applegate were just a handful of figures who had memorable roles on the sitcom. The cameo by Williams was short considering it ended before the opening credits rolled, but it involved had an interesting backstory. It turned out that Williams and Crystal were at the right place at the right time - on a nearby set - because their cameos weren't even planned.
Robin Williams' Cameo In Friends Wasn't In The Original Script
While the Friends season 3 episode was being shot, Williams and Crystal happened to be working at a neighboring set. The comedic duo wandered onto the Friends set and the writers asked them if they'd be up for a quick cameo. They agreed so the pair were thrown right into the opening scene on the spot. It's very rare to acquire a role and shoot the scene within the same day but Williams and Crystal had no qualms about the request. They ad-libbed their entire scene, inventing the story about Tomas and his wife. The improv must have rubbed off on the cast because Matt LeBlanc even ad-libbed his interruption of the men's private conversation and Courtney Cox personally added the line about forgetting her original story.
The cameo by Williams and Crystal may have been an accident but it made for great TV. It also coincidentally gave the actors an extra amount of publicity at the right time. A day after the Friends episode aired with their cameos, the pair's movie, Father's Day, hit theaters. The cameo from Williams has become even more special following the actor's tragic death in 2014.