The sixth president of the United States - John Quincy Adams. It sounds as if Adams's presidency was rather uneventful because he had to contend with opposition in Congress (sounds a little familiar). Prior to his presidency he was a brilliant diplomat, helping to design the Monroe Doctrine. After leaving the presidential office he became a Congressman and spent the rest of his political life fighting slavery (even predicting an inevitable civil war).
He was also the first president to be photographed, so now I have to start worrying about getting accurate likenesses.
Trivia time: at his inauguration John Quincy didn't swear on a Bible, but instead on a stack of law books. He viewed swearing on a Bible as a violation of the separation of church and state.