I have to disagree with the Don Quixote votes. The man of la Mancha never really was aware of his world (IMO). He was perpetually delusional (whether by insanity or choice could be debated I suppose) and refused to admit that the world could be imperfect.
A true Knight chooses good and virtue with full knowledge of evil and vice. They make hard choices, choosing right over worng. Otherwise there would be no real choice made, which proves nothing. And no, I don't think they really need shining armor. So, with that in mind ...
Paksenarrion Dorthansdotter (amazing I still can spell that)
Sturm Brighblade (despite his shining armor)
Kaz the Minotaur was twice the Knight Huma was
El Cid
Luke Skywalker
Lord Algemar of Fal Dara, and brothers Gawyn and Galain (Wheel of Time)
At first I was thinking al'Lan Mandragoran, but I have changed my mind. Whether it was his sword's legacy, Moiraine's commands or Nyneave's love, Lan never made hard choices. He let others make them for him.
Dragonbait (Finder's Stone)
William Wallace as portrayed by Mel Gibson. Frankly I don't know enough about the hirtorical figure to make an argument for that, so lets not start a new Saladin debate.
I may commit myself to D&D Purgatory for admitting this, but I have never read an Arthurian Legend or The Lord of the Rings, so I will leave that debate to others

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Irda Ranger
Edit, PS - Oh yeah, and Hong, chill out. Ignorance can't be cured in a day. I do think that real historical figures should be avoided though. They are too complex to fit the "Quintessential Knight"s narrow little niche.