Leo Sylvester Hannan (23 October 1900 – 9 October 1962) was a New Zealand murderer who was convicted of the 1950 murder of watchman Frederick Stade in Wellington, for which he was sentenced to life imprisonment. A few months before he died of cancer in 1962, he confessed to his lawyer that he had committed three additional murders dating back to 1942, for which he was never charged.