How can I introduce King Arthur to my roommate?

Earlier today I read Tennyson’s Morte d’ Arthur, (and subsequently the Idylls of the king). I thought Morte d’ Arthur was amazing, so I mentioned it to my roommate and offered to let him read it. He responded that he did not know who King Arthur was. (How he made it to college without crossing paths with Arthur, son of Uther, king of the Britons, I know not.) Where is a good point to start with the Arthurian legends? Mallory? Tennyson? T.H White? (or even Twain, with his Connecticut Yankee…?)