Have you ever found yourself watching a show only to be startled by the realisation a small part is played by someone really famous?
Maybe you spotted a celeb in one of their early, bit-part roles, like Shailene Woodley playing a young Kaitlin Cooper on The O.C.
Or maybe were you surprised to see someone in a one-off episode, like Ryan Reynolds appearing on The X Files?
Maybe it was someone who had a slightly bigger arc, like Anna Faris playing the birthmother of Monica and Chandler's kids on Friends.
