Do you remember these celebrities appearing in Friends?

Can you remember these five guest stars appearing in Friends?

We all know the six main stars of 'Friends' were the irreplaceable Courteney Cox, Jennifer Aniston, Lisa Kudrow, Matt LeBlanc, David Schwimmer and the late Matthew Perry.

But the gang had many adventures in New York with an array of guest stars who played siblings, new pals and love interests.

Here are five stars you forgot had cameos in 'Friends'...

America’s sweetheart Reese Witherspoon took on the guest role of Rachel’s (Aniston) younger sister Jill Green for two episodes in Season 6.

Jill arrives in New York looking for help from Rachel and the gang when she wants to break free from her father’s controlling ways but causes a stir when she wants to date her sister’s ex-boyfriend Ross Geller (Schwimmer).

‘Pretty Woman’ star Julia Roberts made a splash when she appeared as Chandler’s (Perry) childhood friend Susie Moss, who he embarrassed at school by lifting up her skirt in during a school performance, exposing her underwear to everyone.

Susie seeks revenge on Chandler by inviting him on a date and then seducing him in the men’s bathroom at a restaurant, leaving him stranded in a stall wearing nothing but ladies’ underwear!

Brooke Shields made a brief appearance as Joey’s (LeBlanc) stalker, Erika Ford, who thinks his TV alter ego Dr. Drake Ramoray is a real person.

Despite her mental state, Joey agrees to start dating Erika but he incurs her wrath after she watches him 'cheating' on her with another character from his TV show.

Action legend Bruce Willis appeared in three episodes during Season 6 as Paul Stevens, the father of Ross’ younger girlfriend Elizabeth.

However, Paul winds up dating Ross’ ex Rachel which makes things awkward when they all agree to go on a double date.

Willis donated his appearance fee to five charities after losing a bet with his 'The Whole Nine Yards' co-star Matthew Perry.

Brad 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 (Cox|) 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!