Brad Pitt

Pitt - who was married to Jennifer Aniston at the time - guest-starred in one episode in Season 8 as Will Colbert, who went to school with Ross, Monica and Rachel.

However, it is revealed that Rachel bullied him in high school so he invented a rumor that she was a hermaphrodite.

Will is left betrayed when he discovers that Ross - who helped him set up the I Hate Rachel Green Club - was expecting a child with Rachel!