Ludwig Wittgenstein.

While not technically an American, he was brought up in class, and I am therefore going to assume he is fair game. Ludwig Wittgenstein was a fascinating thinker and a prodigy by all standards. His thoughts on language are shockingly complicated because they are so eerily simple--language unnecessarily complicates things. In class, we mentioned his idea of the "fruit fly in the bottle;" in this scenario, we are the fruit fly, and language is the bottle, though which we are forced to see the rest of the world in a warped way that is particular to the bottle. It is, of course, undeniable that although language brings us together as a means of communication, it is a hindrance in that we must label things in order to communicate. Wittgenstein, through this argument, is able to belittle philosophy as being almost entirely irrelevant, based solely on a misunderstanding of language. After grappling with the idea for a while, I came to realize that he was right--philosophers endlessly debate the meaning of life, love, happiness, and power, discussions which would all be pointless if we were able to settle on a universal and truthful definition of each of those words.
Derek Jarman's 1993 film Wittgenstein is a thought-provoking medley of short sketches which show Wittgenstein at many different stages of his life, and follow the trajectory of his philosophy of linguistics, among other of his many intellectual triumphs. While it is rather long and extremely biographical, the sketches of Wittgenstein at Cambridge are useful in attemptig to understand the specifics of his philosophy, and how we should interact with it.