‘Friends’ Most Memorable Guest Stars: Brad Pitt, Julia Roberts, Ben Stiller and More

Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matthew Perry, Matt LeBlanc and David Schwimmer rose to massive fame during Friends, which aired on NBC for 10 seasons from 1994 to 2004.

From the start, the sitcom drew the attention of celebrities — and landed some huge guest stars. In the first season, both George Clooney and Helen Hunt appeared in brief roles — and they were just the start.

One of the most memorable guest stars is Brad Pitt. The actor portrayed Will Colbert on "The One With the Rumor," the annual Thanksgiving episode that aired in 2001 during season 8. At the time, Pitt and Aniston were married. (The two split in 2005.) His cameo earned the Pitt an Emmy nomination for Outstanding Guest Actor in a Comedy Series and gave him a chance to promote his movie, Spy Game. Of course, the cameo also gave viewers the chance to see the then-beloved couple as enemies.

Other guest appearances led to a lifelong friendship. Reese Witherspoon appeared in season 6 as Rachel's sister Jill Green and although the characters didn't get along, the actresses became close friends. Nine years later, they starred in and produced Apple TV's The Morning Show.

Throughout the show, some giant stars also appeared in longer arcs, including Tom Selleck, Paul Rudd and Bruce Willis. Scroll through the gallery below to relive some of the most memorable guest appearances on Friends over the years.