Read more about Mace Windu at: Wikipedia
Official Site: Lucasfilm
Mace Windu is a fictional character in the Star Wars universe. He is most famously portrayed by actor Samuel L. Jackson in the prequel films, but Windu has also been voiced by other actors in assorted video game and animated projects.
Mace Windu is one of the earliest named and created characters in Star Wars history, being the narrator of the original 1973 drafts of the original Star Wars film (later named Star Wars Episode IV: A New Hope). Through the process of redrafting and copyediting, his character was removed from the original film and its two successors, but he was reintroduced in 1994 when series creator George Lucas began writing the prequel trilogy.
When Lucas offered Samuel L. Jackson the role of Mace Windu, Jackson signed on, but with certain stipulations on the portrayal of his character. Aware that the climax of the prequel trilogy would eventually call for Mace Windu's death, one of the conditions was that his character die in a spectacular fashion, rather than being killed off ingloriously.
Also, according to an interview on The Late Show with David Letterman on May 13, 2005, Windu's purple lightsaber was a personal request from Jackson to Lucas as a quid pro quo for appearing in the films, as well as a way of making the character unique and easily distinguishable. Jackson, a huge Star Wars fan, especially wanted his own color so that his character could be easily spotted and recognizable in the final battle scene of Star Wars Episode II: Attack of the Clones amid all of the other Jedi.