Friends remains a classic, even 16 years after the last episode aired. For 236 episodes, Ross, Rachel, Chandler, Monica, Phoebe and Joey made us laugh till our sides hurt and occasionally they had help. Every season saw a new bunch of A-listers lend their talent to the show. If the screaming from the live audience was anything to go by, the names just kept getting bigger and bigger. From Brad Pitt to Robin Williams, Julia Roberts to Charlie Sheen, Sean Penn to even Paul 'Antman' Rudd - there was always a surprise A-lister that made the episode even better. Check out these 27 stars who starred on Friends. Which one of these episodes was your favorite?