Turned down the role of Brom because of his commitment to X-Men 3.
Ian McKellen turned down the role of Albus Dumbledore afer Richard Harris passed away. He was quoted as saying "I had enough trouble living up to one legend. Two would be too much to hope for." (referring to his role as Gandalf in Lord of the Rings)
Unable to accept Peter Jackson's offer because he was already committed to doing a play in London.
Ian McKellen was originally set to play Antonio alongside Al Pacino.
Did you know that Ian McKellen was not the only choice for these movies? (click to learn more)