Sir Ian McKellen rejected the role of Professor Dumbledore in the Harry Potter movies because Richard Harris didn't respect him as an actor.
The 77-year-old star was offered the chance to replace Harris as the headmaster of the wizarding school Hogwarts following his death in 2002 - but Sir Ian declined the invitation because his would-be predecessor didn't rate him as an actor, having previously described him as "technically brilliant, but passionless".
He explained: "When he died - he played Dumbledore, the wizard - I played the real wizard [Gandalf in the Lord Of The Rings trilogy] of course - but when they called me up and said would I be interested in being in the Harry Potter films, they didn't say what part.
"I worked out what they were thinking and I couldn't. I couldn't take over the part from an actor who I'd known hadn't approved of me."
Harris starred in the first two Harry Potter films and was replaced by Michael Gambon for the rest of the series.
Asked if he could have played Dumbledore, Sir Ian told HARDtalk: "Well, sometimes when I see posters of Michael Gambon, the actor who gloriously plays Dumbledore, I think it's me. You know, we get asked for each other's autographs!"
Meanwhile, Sir Ian has called on other gay actors to follow his example and make their sexuality known publicly. The award-winning star - who first revealed he was gay in 1988 - claimed actors could set an example to those young people who are confused about their sexuality, and ultimately, help them to live a happier life.
He said: "Practically every person I know who has declared their sexuality, life becomes better in every possible way once you are honest."