Jack Moriarty was a man who claimed to be a former patient of House. Moriarty shot House, but was then shot by security as he tried to escape. House's bed was right next to his while they were recovering. It later turned out that this was a hallucination House experienced while recovering from his wounds. Not much is known about him, although like House himself he is based on a Sherlock Holmes character named Professor Moriarty who was Holmes arch enemy.