The Rachel Bilson Cameo In That '70s Show You Likely Forgot About

The Fox sitcom "That '70s Show" was a major success, ultimately running for 200 episodes over 8 seasons. Many members of the show's cast, including Ashton Kutcher, Mila Kunis, Topher Grace, and Laura Prepon, went on to become major names based on the strength of their work on the show.

Rachel Bilson, however, rose to prominence on a completely different Fox show, the teen drama "The O.C." Premiering in 2003, the show was created by Josh Schwartz, who would go on to develop "Chuck," "Gossip Girl," and "Nancy Drew." It starred Bilson as Summer Roberts, a member of the rich community that Ryan Atwood (Ben McKenzie) finds himself in after being adopted in the pilot episode. Ryan's foster brother Seth Cohen (Adam Brody) eventually becomes Summer's love interest, while her best friend Marissa Cooper (Mischa Barton) developed a relationship with Ryan.

However, Bilson did also make an appearance on "That '70s Show," in a small role that has slipped out of the memory of many fans of both Bilson and the sitcom. This is the Rachel Bilson cameo you likely forgot about on "That '70s Show."

Bilson was already known for The OC

Rachel Bilson appeared in Episode 21 of season 6 of"That 70s Show," titled "5:15."

In the episode, Bilson plays Christy, who is an attendee at the wedding of the brother of Mitch Miller, played by Seth Green. Donna (Laura Prepon) agrees to be Mitch's date to the wedding, leading to Jackie (Mila Kunis) and Fez (Wilmer Valderrama) coming along as chaperones. However, Christy catches the eye of Fez, who decides to pretend to be rich to impress her, an endeavor Jackie helps him with.

The episode aired in 2004, with "The OC" having started in 2003, making Bilson a known figure to TV fans at the time she appeared on the show. In that same month, Bilson also appeared in an episode of the sketch comedy show "MadTV," reprising her role as Summer Roberts alongside "The OC" co-stars Adam Brody and Ben McKenzie for a sketch on the show where Ryan Atwood's old gang, comprised of contestants on "American Idol," come to visit.

Bilson preceded her work on "The OC" with guest appearances on "8 Simple Rules" and "Buffy the Vampire Slayer" and subsequently appeared in shows such as "Chuck," "How I Met Your Mother," "Nashville," and "Drunk History."

Numerous other stars also made a cameo on That 70s Show

Rachel Bilson was far from the only star to make a single-episode appearance on "That '70s Show." "M.A.S.H" star Jamie Farr, who played Maxwell Klinger on the series as well as "AfterMASH," appeared on the sitcom as a fictionalized version of himself in the show's fifth season episode "The Girl I Love."

"3rd Rock From The Sun" stars Joseph Gordon-Levitt, who played Tommy Solomon, and French Stewart, who played Harry Solomon, both independently made appearances on the show as well. Stewart played Daniel in the season 4 episode "Hyde Gets the Girl," making an uncredited appearance in the following episode as well. Gordon-Levitt played Buddy Morgan in the first season episode "Eric's Buddy," with comedian Mitch Hedberg also appearing in the episode.

Wayne Knight, best known for his role as Newman on "Seinfeld," also made an appearance on "That '70s Show," appearing in the Season 4 premiere "It's A Wonderful Life" as an angel who shows Eric how life would've been if he'd never been born, in a riff on the 1946 movie of the same name. The titular star of "Sabrina the Teenage Witch" and "Clarissa Explains It All," Melissa Joan Hart, also appeared on the show in the Season Two episode "Eric Gets Suspended," playing Mary.

On the other side of the coin, "The Office" star Jenna Fischer made an appearance in the Season 7 episode "Don't Lie To Me," playing Stacy Wanamaker in her last notable role before the premiere of "The Office."