15 A-Listers Who Guest-Starred on Friends and You Totally Forgot About It

1. Bruce Willis – "The One with the Ring" (Season 6)

Bruce Willis stepped away from his action-packed Hollywood lifestyle to portray the overly sensitive, tough-on-the-outside, soft-on-the-inside Paul Stevens, who was dating Rachel. This all started when Ross fell in love with Paul's daughter, Elizabeth, in season 6. The situation became hilarious when Ross and Rachel found themselves on a double date with Paul and Elizabeth. Willis' overcompensation of machismo to hide his sensitivity was a hoot, providing an entertaining contrast to Ross's nervous energy.

2. Reese Witherspoon – "The One with Rachel's Sister" (Season 6)

Another big-screen star who visited Central Perk was Reese Witherspoon, playing Rachel's younger and somewhat clueless sister, Jill. Initially, she comes to New York after their father cuts her off financially, intending to follow Rachel's footsteps and establish herself. Instead, she goes on a shopping spree with Rachel's credit card and even attempts to seduce Ross.

3. Julia Roberts – "The One After the Superbowl" (Season 2)

Julia Roberts stole the show in "The One After the Superbowl" as Susie Moss, a former schoolmate of Chandler, who's out for revenge. Chandler bullied Susie in their elementary school days by lifting her skirt during a school play. Her vengeful plot, culminating in her stealing Chandler's clothes while he's in the restroom, is one of the show's most humorous subplots.

4. Alec Baldwin – "The One in Massapequa" (Season 8)

Known for his gruff roles and acerbic wit, Alec Baldwin showed up in Friends as Phoebe's overly enthusiastic boyfriend, Parker. Invited to Ross and Monica's parents' anniversary party, Parker is relentlessly positive, admiring everything from the Gellers' house to their commemorative banquet menu. His endless cheerfulness, although initially refreshing, soon becomes annoying to everyone, including Phoebe.

5. Sean Penn – "The One with the Halloween Party" (Season 8)

Sean Penn appearing in Friends as Eric, Ursula's fiancé, was an unexpected but pleasant surprise. In the episode, Phoebe feels obliged to tell Eric some home truths about her twin sister Ursula, after finding out that Ursula has been lying to him. Penn's earnest portrayal of a kind-hearted, naive school teacher who had no idea about Ursula's manipulative nature, added an extra layer of sympathy and humor to the plot. Penn's reactions, when faced with the hard truths about Ursula, were particularly amusing.

6. Brad Pitt – "The One with the Rumor" (Season 8)

Back in the day, when "Brangelina" was still "Brad and Jen," Brad Pitt played Will Colbert, Ross' high school friend who despised Rachel Green. The icing on the comedy cake here was the irony that Pitt was married to Jennifer Aniston at the time. Will, once an overweight teen, harbored a deep resentment towards Rachel for her high school bullying. The Thanksgiving episode crescendoed with the reveal of the "I Hate Rachel Green Club," founded by Ross and Will, bringing the episode to a hilarious climax.

7. Paul Rudd – "The One with the Pediatrician" (Season 9)

Paul Rudd, everyone's favorite ageless wonder, joined the Friends' universe as Phoebe's boyfriend and eventual husband, Mike Hannigan. Initially introduced to Phoebe on a blind date set up by Joey, Mike quickly became a series regular. Rudd's character was a refreshing change of pace, a normal guy amidst the group's shenanigans. His level-headed personality balanced well with Phoebe's quirky nature, making their relationship both believable and endearing. His horrified reactions to Ross' performance on the Bagpipes in "The One Where Ross is Fine" is comedic gold.

8. Christina Applegate – "The One with Rachel's Other Sister" (Season 9)

Rachel's other sister, Amy, played by Christina Applegate, was another delightfully snobby, self-centered character in the "Friends" universe. Applegate's comedic timing and delivery were perfect, making Amy's insensitivity and materialism as funny as it was appalling. Her inability to get Emma's name right and her argument with Rachel about who would get Emma if Ross and Rachel died were some of the episode's highlights. Applegate's performance earned her an Emmy for Outstanding Guest Actress in a Comedy Series, which speaks volumes about the quality of her performance.

9. Danny DeVito – "The One Where the Stripper Cries" (Season 10)

Friends is known for many things, but a striptease by Danny DeVito wasn't one we ever saw coming. DeVito played Roy, a middle-aged, disheartened stripper hired for Phoebe's bachelorette party. Roy's initial performance was a flop, leading to an emotional breakdown and heart-to-heart with Phoebe. DeVito's portrayal of the character's sadness and his enthusiasm when given a second chance made this cameo both funny and heartwarming.

10. Jon Lovitz – "The One with the Stoned Guy" (Season 1) and "The One with the Blind Dates" (Season 9)

Jon Lovitz played Steve, a restaurateur, in season 1 and returned to the role in season 9, in two hilarious guest appearances. In his first appearance, Steve arrives at Monica's for a private dinner she's cooked to showcase her culinary skills, only for him to show up stoned and fascinated more by taco shells than her gourmet fare. In season 9, Rachel and Steve are set up on a blind date, during which Steve's eccentric behavior makes the situation hilariously uncomfortable.

11. Gary Oldman – "The One with Monica and Chandler's Wedding" (Season 7)

When it comes to memorable performances, Gary Oldman's portrayal of the drunken actor, Richard Crosby, stands out. He played a co-star to Joey in a war film and stole the show with his inebriated acting lessons, teaching Joey the importance of 'spitting' to enunciate. Their interactions, coupled with Chandler's disappearance and last-minute cold feet about his wedding to Monica, made the finale a classic.

12. Dermot Mulroney – "The One Where Rachel Goes Back To Work" (Season 9)

Dermot Mulroney portrayed Gavin Mitchell, a charming co-worker who initially butts heads with Rachel before eventually engaging in a brief romantic relationship. Their rivalry turns into a passionate kiss in the copy room, leading to a few episodes of romantic tension. Rachel's internal struggle between her unresolved feelings for Ross and her attraction to Gavin made this storyline all the more interesting.

13. Jennifer Coolidge – "The One with Ross's Tan" (Season 10)

Jennifer Coolidge, known for her comedic roles, guest-starred as Amanda, an old friend of Monica and Phoebe from England. With her affected accent and bizarre new age lifestyle, Amanda was a hilarious addition to the Friends universe. The episode is a whirlwind of forced social interaction, ending in Monica and Phoebe trying to 'cut her out' of their lives. Coolidge's exaggerated performance, complete with "lip wobble" and fake British-American accent, delivered lots of laughs.

14. Hank Azaria – Multiple Episodes (Seasons 1,3,9,10)

Hank Azaria played David, the scientist guy, who was one of Phoebe's most serious love interests. David's character was a sweet, charming, and somewhat nerdy foil to Phoebe's quirky personality. His decision to leave for Minsk set up a tearful goodbye in the snow, only for him to return in later seasons, reigniting their relationship.

15. Elle Macpherson – "The One with the Apothecary Table" (Season 6)

Australian supermodel Elle Macpherson appeared as Joey's roommate, Janine. She added an interesting dynamic to Joey's storyline as one of the few roommates he had aside from Chandler. Joey's initial crush, followed by their short-lived relationship, was an enjoyable arc for both characters. Macpherson's portrayal of the laid-back dancer created several entertaining moments, particularly the tension between Janine and Monica due to their differing personalities.