The Best 'Friends' Guest Star Moments to Relive Before Netflix Drops It in January

George Clooney: Season 1, Episode 17: 'The One with Two Parts: Part 2'

George Clooney and Noah Wyle delighted TV fanatics when the ER stars showed up on Friends — as handsome doctors, no less, who inevitably try to date Rachel and Monica. What they don't know is that Rachel and Monica have committed insurance fraud after they switch identities so Rachel can use Monica's health insurance following an ankle injury.

Jason Alexander: Season 7, Episode 13: 'The One Where Rosita Dies'

In another delightful NBC quasi crossover, Jason Alexander hops from the world of one hit comedy, Seinfeld, to another as Earl, a miserable office manager who Phoebe encounters while trying to sell him toner as a telemarketer. As only Phoebe could do, she successfully convinces Earl not to kill himself.

Brad Pitt: Season 8, Episode 9: 'The One with the Rumor'

Friends fans who were pop culture savvy received a Thanksgiving treat during the eighth season's iconic holiday episode when Brad Pitt, who was married to Jennifer Aniston in real life, guest starred. During the episode, it's revealed that he and Ross (David Schwimmer) were part of an "I Hate Rachel" club back in the day — and that they even convinced an exchange student to join their club. Watching Aniston and Pitt pretend to hate each other on screen was delightful fun for longtime Friends fans.

Reese Witherspoon: Season 6, Episodes 13 and 14: 'The One With Rachel's Sister' and 'The One Where Chandler Can't Cry'

Rachel's younger sister, Jill (Reese Witherspoon) arrives in New York dead-set on following her sister's footsteps of living in New York without their father's financial help. Her likeness to her sister is a little too uncanny, however, when she tries to date Ross. Eventually, Jill decides to cut her losses and return to a bankrolled life.

Julia Roberts: Season 2, Episodes 12 and 13: 'The One After the Superbowl'

Super Bowl viewers were treated with a Julia Roberts cameo on Friends when she played Susie Moss, aka Susie Underpants, aka Chandler's old classmate who he relentlessly bullied and who ultimately got revenge on him. Susie recounted the story to Chandler, telling him he lifted her skirt during a school play and "the entire auditorium saw my underpants." Decades later, she seduces him in a bathroom stall and steals his clothes.

Danny Devito: Season 10, Episode 11: 'The One Where the Stripper Cries'

Who could forget Danny Devito's iconic Friends cameo as the stripper at Phoebe's (Lisa Kudrow) bachelorette party? It went down as one of the best Friends guest appearances ever, especially when fans noticed Kudrow's wildly unsuccessful attempts to hide her real-life laughter at DeVito's performance.

Winona Ryder - Season 7, Episode 20: 'The One with Rachel's Big Kiss'

Rachel spends the majority of this season 7 episode trying to convince the group that she kissed her sorority sister Melissa, (Winona Ryder) in college. The group was shocked when Melissa admitted that they did, in fact, share a kiss — and that she deeply enjoyed it.

Robin Williams and Billy Crystal — Season 3, Episode 24: 'The One with the Ultimate Fighting Champion'

The legendary Robin Williams and Billy Crystal appeared in a very brief, but very memorable cameo appearance during season 2 when a distraught Williams confided to his friend, Crystal (whose names were actually Tim and Tom) that he suspected his wife was cheating on him — just to find out that Crystal's character was the one Williams' character's wife was cheating with. The fact that the conversation took place with the Friends group literally inches away from them made it even better.

Many fans know that the conversation was totally improvised, as the cameo wasn't even scripted; Williams and Crystal just happened to be filming Father's Day nearby and the writers asked if they'd do an appearance.