Friends was one of the most popular shows of the 90s. The show was loved by millions and aired for 10 years, helping to make all the stars household names. NBCOne of the best things about Friends was that they had so many guest stars. Each season had some huge names come and join the cast for a few special episodes. Sometimes they would appear as themselves but a lot of the time they would play a character.Some really big names came to Central Perk over the years, including Robin Williams, Billy Crystal, Tom Selleck, Susan Surandon, Brad Pitt