The Reverend John Selby Watson (April 1804 – 6 July 1884) was a British classical translator and murderer. He was sentenced to death in 1872 for killing his wife, but a public outcry led to his sentence being reduced to life imprisonment. The case is notable for Watson's use of a plea of insanity as his defence, bringing "the insanity defense into perhaps its greatest prominence since M'Naghten."