But as versatile an actor as he was, he was barred from trying out for a role in one of the biggest film franchises of all time: the “Harry Potter” series. When it came time to cast for “Harry Potter and the Sorcerer’s Stone,” the film’s casting director Janet Hirshenson told the Huffington Post, “Robin [Williams] had called [director Chris Columbus] because he really wanted to be in the movie, but it was a British-only edict, and once he said no to Robin, he wasn’t going to say yes to anybody else, that’s for sure. It couldn’t be.” The British-only rule was the novel’s writer J.K. Rowling’s idea, and it’s an understandable one. Still, as great as Robbie Coltrane was as Hagrid, it would’ve been a blast seeing Williams as the half-giant gamekeeper.