Ian McKellen, has always played great parts whether it be hero or villain Ian, gives a great performance.
I've seen him in a few movies, but my favorite ones are the lord of the rings Trilogy where he played Gandalf the Grey/Gandalf the White and X-men Where he played the main villain Magneto.
Lord of the Rings: Fellowship of the Ring- he played the wise wizard Gandalf the Grey, though he had little patience with Merry and Pippin, he was know to crack so jokes and be humorous at times, but Ian nailed the part perfectly, just the look that was giving to Gandalf made him look wise, and when Gandalf died, having never read the books I though he was gone for good.
Lord of The Rings: Two Towers and Return of The King - he returned from the dead as Gandalf the White, a much more powerful version of himself, and his character was more serious then his Fellowship of the ring counterpart.
X-Men: he plays the X-men's archenemy Magneto, in all three movies; he shows that he can play a villain as well as a hero.
Ian McKellen is a superb actor, with a lot of talent.