Between 2003 and 2007, over four seasons and 92 episodes, The O.C. followed the soapy lives of a group of teens and adults living in tony Newport, California. The series turned actors Adam Brody, Ben McKenzie, Rachel Bilson, and Mischa Barton into stars, but several other future celebs stopped by to cause drama for either one episode or in recurring roles.

1. Chris Pratt // “Che Cook”

A post-Everwood and pre-Parks and Recreation/Guardians of the Galaxy Pratt sharpened his comic chops as a shaggy-haired Brown University activist named Che. He appeared in nine episodes during the show's fourth season, where he got Summer Roberts (Bilson) suspended from school, and later believed Seth Cohen (Brody) was his soulmate.

2. Shailene Woodley // “Kaitlin Cooper”

Woodley appeared as Kaitlin Cooper, Marissa Cooper’s (Barton) sister, in the pilot. At the end of the season, Kaitlin was shipped off to boarding school. The character didn’t resurface until season three, with Woodley having to audition to reclaim her role. But the casting department went in a different direction, choosing Willa Holland instead, who then played Kaitlin until the series ended. In 2011, Woodley reminisced to Moviefone about her prepubescent role, saying: “I didn't go through puberty until late—I was the 15-year-old who had no boobs. So, at 11, I was like a little mouse-child. I looked like an eight-year-old. That same year, I filmed a movie in which I was playing a 9-year-old. So, there was no weirdness when Willa Holland got it because she was so obviously right for the role, and I was so obviously not.”

3. Olivia Wilde // “Alex Kelly”

For 13 episodes during the 2004-2005 season, a then-unknown Wilde played Alex Kelly, the owner of a music venue, The Bait Shop, who briefly dates Seth before finding a more fitting paramour in Marissa. The two embark on a passionate lesbian affair only to have it fizzle a few episodes later. Showrunner Josh Schwartz made it clear in a 2011 interview with Out.com that the lesbian storyline wasn’t developed to garner ratings. "We cooked it up well before the show ever premiered this year," he said.

4. Emmanuelle Chriqui // “Jodie”

In the episode “The Ex-Factor,” Alex Kelly’s possessive ex-girlfriend Jodie shows up, which is why Alex breaks things off with Seth. Jodie stays with Alex for a week—it gives her another episode—before she goes back to L.A. Just a few months after her two-episode arc, Chriqui began playing Sloan McQuewick on Entourage.

5. Michael Schur // “Paul”

In 2007, Schur hadn’t yet co-created Parks and Recreation, but he was writing and producing for The Office, and occasionally guest starring as Dwight Schrute’s cousin, Mose, who runs a beet farm. In “The Case of the Franks,” Schur tries to recruit Summer to join his environmental agency, George. Schur’s wife, J.J Philbin (daughter of Regis) wrote the episode.

6. Amber Heard // “Salesgirl”

Mrs. Johnny Depp didn’t even get a proper name in her episode, she was only known as “Salesgirl,” but she did get to interact with Marissa and crew. “Somebody missed the sensitivity training seminar,” Seth quips behind Salesgirl’s back. The episode entails the gang hanging out at the mall only to get trapped there after it closes.

7. Morena Baccarin // “Maya Griffin”

For three episodes during the third season, the Firefly and Emmy-nominated Homeland actress played the daughter of Sandy Cohen’s (Peter Gallagher) rival, Henry Griffin. Drama ensues when Maya begins dating Matt Ramsey, who works for Sandy’s company, The Newport Group. Fun fact: Baccarin went on to act with Ben McKenzie on Gotham.

8. Max Greenfield // “Young Sandy Cohen”

At this point in Greenfield's career, he had guested on Gilmore Girls and Veronica Mars, but was still four years away from finding stardom as a regular cast member on New Girl. In his episode of The O.C., he plays a college-aged Sandy Cohen in a flashback scene where he meets and charms future wife Kirsten at Berkeley. Kevin Sorbo and Michael Schur also show up in the same episode.

9. Nikki Reed // “Sadie Campbell”

In 2003, Reed established herself as a writer and actor in the teen film Thirteen, then moved on to The O.C. in 2006. In her six-episode character arc, she briefly dates Ryan, which makes Marissa jealous. Reed’s character was developed to rival Marissa, but in the end she doesn’t succeed. After Reed left Newport, she starred as Rosalie Hale in all of the Twilight films. Cam Gigandet, who played Marissa’s killer ex-boyfriend Kevin Volchok for 15 episodes, appeared with Reed in two Twilight movies.

10. Jaime King // “Mary Sue”

The actress, model, and friend of Taylor Swift got messy in her O.C. role. While visiting their grandmother in Florida, Seth and Ryan meet Mary Sue, whose grandmother lives near their Nana. Mary Sue and Seth join forces in a televised dance contest where she covers herself with whipped cream and asks Seth to lick it off. King now stars on Hart of Dixie alongside Rachel Bilson, which Josh Schwartz produces.

... AND A FEW FAMOUS FACES WHO STOPPED BY:

Michael Nouri // "Dr. Neil Roberts"

Nouri, who played Jennifer Beals’ love interest in Flashdance, portrayed Summer Roberts’ dad, Dr. Neil Roberts, for four seasons. Even though he sporadically appears throughout the series, he didn’t receive more airtime and storylines until the third season, when he romances Julie Cooper. Eventually he moves to Seattle and doesn’t return to Newport, not even for Summer’s wedding.

Jeri Ryan // “Charlotte Morgan”

Jeri Ryan, of Star Trek: Voyager fame, had a juicy role on The O.C. as a woman who befriends Kirsten Cohen (Kelly Rowan) in rehab and then attempts to swindle her. When Charlotte’s unable to con Kirsten, she plans a fundraiser with Julie Cooper in order to steal the donations, but Julie spoils the plot. In 2007, Josh Schwartz revealed to Vulture that the Jeri Ryan storyline ruined the season for him. “We were told to add this Jeri Ryan character to the show that we had no idea what to do with,” he said. “We were just told we had to add an adult female character. It went nowhere, and we had no plan for it, and it just didn’t fit the show.”

Kevin Sorbo // “Frank Atwood”

The Hercules beefcake played Ryan Atwood’s (McKenzie) criminal dad but didn’t arrive in Newport until the series' final season. For seven episodes during season four, Frank Atwood slowly reveals to a dismayed Ryan that he’s his biological father. Frank finally redeems himself by hooking up with Julie Cooper (Melinda Clarke) and fathering a son with her.

Marguerite Moreau // “Reed Carlson”

After starring in Wet Hot American Summer, Moreau played Reed Carlson, VP of comic book company Bad Science, on The O.C. She helps set up Seth's meeting with George Lucas and eventually publishes his book. The TV vet later had guest roles on Grey’s Anatomy, Shameless, and Parenthood, and is reprising her Wet Hot American Summer role in the upcoming Netflix series.

George Lucas // “George Lucas” 

Seth Cohen co-writes a graphic novel entitled Atomic Country, and George Lucas takes notice. Seth gets a meeting with Lucas but is torn between attending the meeting and taking Summer to the prom. He asks Lucas for advice, in which Lucas tells Seth he regretted not attending his own prom. Lucas appeared on the episode as a way to promote Star Wars: Episode III – Revenge of the Sith, which was released a week after the episode aired.