[Beanamir of Gondor]

The only reason Gandalf didn't come to my mind at first, I think, is because of that Steward-like quality or position. Morgoth was second to none in his quest for Evil; in the Third Age, Sauron was the same. Both wanted to rule all. Gandalf, however, was more than happy to serve the King, as long as that King is on the side of Good. So we don't immediately think of Gandalf in terms of Eru, God, the Omnipotent.

Probably that's why Gandalf might be the greatest example of Good in Tolkien's works: because the Good does not wish for power, only the ability to use it properly, if it is offered. (I hate to draw too many Christian parallelisms, buuuuuut now that Sir Kohran brings it up...)