"Friends" remains a bedrock of '90s and early '00s pop culture.

The show's main stars, like Jennifer Aniston and David Schwimmer, are still major players in Hollywood today. But what's really impressive is how many cameos by famous actors the series packed into its ten seasons.

From then-current celebrities like Brad Pitt and Susan Sarandon, to future notables like Mae Whitman and Cole Sprouse, it seems like almost everyone working in Hollywood between 1994 and 2004 was on "Friends" at one point or another.

There is, however, a notable absence of actors of color. Until Gabrielle Union in the seventh season, hardly any black actors had a significant role. After Union, Aisha Tyler has a prominent role in seasons nine and ten, and Craig Robinson didn't make his appearance until the tenth season.

Here are 56 guest stars you probably forgot about or missed altogether.