Helen Hunt’s Season 1 cameo on Friends was a tongue-in-cheek nod to her character on Mad About You, where Lisa Kudrow (Phoebe) had previously played her twin sister Ursula as a waitress. Hunt stopped in Central Perk and tried to order coffee from Phoebe, thinking it was Ursula and this was the first episode where Phoebe’s identical twin was introduced.

Hank Azaria is probably most well known for his voice work on The Simpsons, but Friends fans know him best as David, the physicist who first met Phoebe in Season 1. Over the course of the series, he popped back in from time to time, but due to his scientific research in other countries, they never really got the timing right.

Actor and comedian Jon Lotivz actually appeared on Friends twice during its 10 seasons. First, in Season 1, he played a restaurateur who was stoned during his entire interview with Monica. Then, in Season 9, he played the same character on a blind date with Rachel, where it was revealed that he’d lost his restaurant and money due to his drug problem. It was the hilarious Friends way of bringing him full circle.

Christina Applegate played Rachel’s sister Amy in two episodes — one in Season 9 and one in Season 10. She was the second of Rachel’s sisters who came to visit her and she can be remembered best for repeatedly referring to Emma as “Ella” and being inspired by her niece to become a — wait for it — baby stylist.

Although she is only in one episode in Season 7, Gabrielle Union began the first of a few romantic love triangles that Joey and Ross eventually found themselves in. Yes, Ross and Joey, of all people. This time, they unknowingly dated her at the same time and later in the episode inadvertently drove her away with their competitive attitudes.

Robin Williams and Billy Crystal played Tomas and Tim, respectively, in the cold open of the Season 3 episode “The One With the Ultimate Fighting Champion.” They rushed into Central Perk and asked the Friends cast to make room on the sofa while Tomas confessed to his friend that he thought his wife was having an affair. During the conversation, which the Friends characters were engrossed in as bystanders, Tim admitted that it was him who was sleeping with his friend’s wife, taking the dramatic conversation up a few notches.

Danny DeVito played Roy Goodbody, the crying stripper, in the Season 10 Friends episode “The One Where the Stripper Cries.” When Monica and Rachel hired a stripper for Phoebe’s classy bachelorette party last minute, Roy showed up with all of the confidence and none of the swagger you’d expect from a professional male stripper. When Phoebe literally cringed away from him during her lap dance, he called her out and eventually cried because he hates his job so much.

At the start of her career, the young and overly precocious Dakota Fanning played Mackenzie in the Season 10 episode where Joey goes with Monica and Chandler to see the house they bought in the suburbs. Mackenzie didn't want her parents to sell the house any more than Joey wanted his friends to move and they bond over it, with Fanning’s character a lot more mature about the whole thing. Obviously.

It’s safe to say that almost all of Phoebe’s boyfriends over the years have been memorable in some way. In Season 8, Alec Baldwin played her easily impressed boyfriend Parker, who was eager to please all of Phoebe’s friends and energetic almost to a fault. Eventually, he became too much for them to handle, Phoebe included, and she had to cut him loose.

Kathleen Turner played Chandler’s dad in a handful of Friends episodes and was referred to as either Charles Bing or by her stage name, Helena Handbasket. She was shown to have a catty relationship with her ex-wife, Chandler’s mom, but she always showed up when Chandler needed her. In Turner’s first appearance as Chandler’s dad, Chandler and Monica flew out to see her Vegas show Viva Las Gaygas in Season 7 to ask her to come to their wedding.

Ben Stiller played Rachel’s boyfriend Tommy in one Season 3 episode. He seemed like a normal, nice guy until he blew up on an elderly couple sitting in his and Ross’ theater seats. Moments later, he was totally calm and no one believed Ross when he told them about the outburst. It wasn’t until later in the episode, when the chick peed in his hand and he started yelling at the chick and the duck that the rest of the friends saw how aggressive he really was.

A year before she landed the lead role in Grey’s Anatomy, Ellen Pompeo played Missy, Ross and Chandler’s former college classmate and the girl they both had a crush on at the same time. She revealed at their class reunion that she and Chandler had hooked up during college when, in fact, he had a pact with Ross not to do anything about their mutual interest in her at the time.

Sean Penn played Eric, Phoebe’s twin Ursula’s fiancé, in two episodes of Season 8. After Phoebe developed feelings for him and saw how Ursula had lied to him about who she really was, Phoebe told him the truth and soon after, the two of them got together, But because Eric had been hurt by Ursula so recently, it was hard for him to be with Phoebe, his now-ex’s twin, and they broke up.

In Season 10, Anna Faris played Erica, the young pregnant woman who picked Monica and Chandler to adopt her unborn twins. She appeared in a handful of episodes as a sometimes ditzy but overall harmless and sweet character. Her last appearance was in the Season 10 episode “The Last One, Part 1,” in which she gave birth to the babies.

Even though I am a strong supporter of Monica and Chandler eventually getting together, I was also all for Jon Favreau's character, Pete, the millionaire tech guy who finally got Monica to date him in Season 3 after harboring a crush on her. Unfortunately, they didn't last as long as I would have preferred and when Pete made his foray into UFC fighting, Monica decided she needed to tap out.

Susan Sarandon played a top tier soap opera star in Season 7 of Friends. When Joey finally got the word that he would no longer have to play a coma patient and would be waking up with her character’s brain in his body, he became her understudy to get her character just right. Despite her anger at being fired, she agreed to teach him, and they even developed a fling before she jetted off to film a movie somewhere else.

Gavin, played by Dermot Mulroney during Season 9 of Friends, had so much potential as Rachel’s co-worker and love interest and he was even on the show for three episodes. But before his relationship with Rachel can go any further than a few kisses, he realized that she might still have feelings for Ross and he backed off.

In Season 7, Rachel’s sorority BFF Melissa, played by Winona Ryder, came for a visit. You might remember her best as the woman who called Rachel “Ray-Ray,” or as the one who Rachel kissed out on the sidewalk to convince Phoebe that Rachel and Melissa had once made out. Throughout the episode, Melissa denied that the incident ever happened, but after Rachel’s surprise kiss, she was convinced that Rachel had the same feelings that Melissa had bottled up for her.

Aisha Tyler played Charlie during Season 9 and seemed like the perfect match for Ross. But when he took his time making a move, Joey swooped in and swept her off her feet. Eventually, Ross, Charlie, Joey, and Rachel were in a love square and once the couples shifted and Charlie and Ross got together, they had a good run for a little while.

Freddie Prinze Jr. played Sandy, Ross and Rachel’s nanny, in the Season 8 episode “The One With the Male Nanny.” Although Ross wasn't wild about having a male nanny, Rachel and Joey especially took to Sandy and his hand puppets. He was also super sensitive, which only made Rachel love him as their nanny more. But eventually, they had to let him go.

At the time of Brad Pitt’s Season 8 Friends cameo, he was married to Jennifer Aniston, so when his character is revealed that he hated Rachel in high school, it was all the more hilarious. At Thanksgiving dinner, he revealed that he and Ross had started the “I Hate Rachel Green” club in high school and that he still harbored negative feelings toward her for the way she ignored him throughout their time in school together.

Paul Rudd played Mike, another one of Phoebe’s memorable love interests, though he eventually became her husband. But if it wasn't for Joey lying to Phoebe about fixing her up with a friend named Mike and then randomly finding this Mike at Central Perk in Season 9, they might have never met.

Gary Oldman is known for his roles in big budget movie franchises like Christopher Nolan’s Batman movies and the Harry Potter films. So when he played an equally renowned actor in Season 7 of Friends opposite Joey in a war movie, it only made sense. But if you need a better refresher, he was the guy who spat every time he enunciated.

In Friends Season 2, Joey knew he had finally come into his own as an actor when he found out he had a stalker, Erika, played by Brooke Shields. Only she was convinced that Joey was really Dr. Drake Ramoray, his Days of Our Lives character. In order to save Joey from her, Ross told her that Joey was actually Hans Ramoray, Drake’s evil twin. Joey convinced her to go to Salem to find the real Drake and, astonishingly, she left, never to be heard from again.

You might know her best as Charlotte on Sex and the City, but in Season 7 of Friends, Kristin Davis played Erin, a one night stand of Joey’s who turned out to be the perfect match for him. He saw it too, but when things started to go a little further, she realized that she wasn't feeling it as much as he was and they broke up. It was one of the big heartbreaks for Joey, who was always more prone to casual hookups than anything else.

Bruce Willis played Rachel’s boyfriend, Paul, for three Season 6 episodes. But, more importantly, he also played the father of Ross’ girlfriend who was his student when they got together. Paul never stopped being suspicious of Ross and it made for some hilarious hi-jinks and classic Ross moments.

Selma Blair played Wendy, Chandler’s Tulsa co-worker who played the only woman who ever tried to come between Monica and Chandler. That is, if you don't count Janice, who showed up at the worst times in the final two seasons of Friends. Wendy tried to hook up with Chandler on Christmas Eve in Season 9, which prompted him to finally quit the job he hated and spontaneously fly home to be with Monica and their friends for the holidays.

When Monica and Chandler considered getting a sperm donor to have a child together in Season 9, Chandler brought his co-worker, Zack, played by John Stamos, home for dinner to grill him and inadvertently make him feel incredibly uncomfortable. Both Monica and Chandler saw him as the perfect candidate until they realized that they wouldn't want to use a stranger’s sperm to have a baby together.

In Season 9, Jeff Goldblum played a theater director who saw Joey’s squirming (as a result of needing to go to the bathroom during the scene) as a revolutionary way to play the character. By all accounts, Goldblum’s character seems like how I imagine the guy is in real life and although it was just one episode, it was a memorable cameo.

Reese Witherspoon appeared in two Season 6 episodes of Friends where she played Rachel’s little sister Jill, a younger and more clueless version of who Rachel was when the gang first reconnected with her back in Season 1. And like her older sister, Jill found herself attracted to Ross and even kissed him. Luckily, her stint on the show was short-lived, but she was probably the best guest star who could have pulled off Rachel’s little sister.

Denise Richards played Ross and Monica’s cousin Cassie in Season 7. Throughout the entire episode, Ross was convinced that although they were cousins, she was as attracted to him as he was her, but when he went in for a kiss, it was as uncomfortable as you’d expect with two cousins potentially making out.

Most of the celebrities who appeared on Friends over the years already had established careers at the time of their cameos, while others were lesser known and used the show as a sort of stepping stone. Either way, I’m sure most fans can agree that they were all memorable in their own ways and now all that’s left to do is embark on your twelfth re-watch to catch all of the celebrity guest stars all over again.