“Friends” has welcomed a wealth of stars. In chronological order, here’s a baker’s dozen of them:

• George Clooney — Feb. 23, 1995, as Dr. Michael Mitchell in “The One with the Two Parts: Part 2.” Also featured then-“ER” colleague Noah Wyle.
• Julia Roberts — Jan. 18, 1996, as Susie Moss in “The One After the Super Bowl.”
• Tom Selleck — Feb. 8, 1996, as Dr. Richard Burke in “The One Where Ross & Rachel … You Know.” Played the same character in eight episodes, ending on May 18, 2000, in “The One With the Proposal.”
• Charlie Sheen — May 9, 1996, as Ryan in “The One with the Chicken Pox.”
• Ben Stiller — April 24, 1997, as Tommy in “The One with the Screamer.”
• Robin Williams — May 8, 1997, as Thomas in “The One with the Ultimate Fighting Champion.”
• Billy Crystal — May 8, 1997, as Tim in “The One with the Ultimate Fighting Champion.”
• Reese Witherspoon — Feb. 3 and 10, 2000, as Jill Green in “The One with Rachel’s Sister” and “The One Where Chandler Can’t Cry.”
• Bruce Willis — April 27, May 4 and 11, 2000, as Paul Stevens in “The One Where Ross Meets Elizabeth,” “The One Where Paul’s the Man” and “The One with the Ring.”
• Susan Sarandon — Feb. 15, 2001, as Jessica Lockhart in “The One with Joey’s New Brain.”
• Sean Penn — Nov. 1 and 8, 2001, as Eric in “The One with the Halloween Party” and “The One with the Stain.”
• Brad Pitt — Nov. 22, 2001, as Will Colbert in “The One with the Rumor.”