For the millennials who have no idea who Robin Williams is, let me give you some information about his career and achievements. Robin McLaurin Williams was an American actor and comedian. He started out as a stand-up comedian in San Francisco and Los Angeles in the mid -1970's. He was acknowledged for leading the comedy renaissance in the San Francisco Area.

He was also well known for movies such as "Dead Poets Society", "Hook", "Mrs Doubtfire", "Jumanji", "Bicentennial Man", "Night at the Museum" and much more. He was also a well-decorated actor, boasting an Academy Award, two Emmy Awards, two Screen Actors Guild Award, five Grammy Awards, and six Golden Globe awards in his acting career.

Now, the question is why was Williams rejected for a role? Simple. Robin Williams might have been one of the best and one of the most famous actors in Hollywood, but it was disclosed that he was turned down for a major role in the "Harry Potter" series due to his nationality. In short, because he wasn't British.

According to Huffington Post, Janet Hirshenson, the casting director for the "Harry Potter" series, said that Robin Williams was very eager to play the role of "Hagrid" in 2001's "Harry Potter and the Philosopher's Stone".  Robin Williams, who passed away in August 2014, spoke with director Chris Columbus about the casting, having previously worked together in several box-office movies. Sadly, the "Harry Potter" series was a British-only edict. 

The actor himself even spoke about being turned down for the role. According to the New York Post via The Guardian, Robin Williams said that there were a couple of parts he would have wanted to play, but there was a ban on casting American actors. The role of "Hagrid" ended up with Robbie Coltrane, the first choice of J.K. Rowling, who played the role throughout the eight movies.