William Joseph "Bill" O'Reilly, often known as Tiger O'Reilly, was an Australian cricketer, rated as one of the best spin bowlers ever to play cricket. He delivered the ball from a two-fingered grip at close to medium pace with great accuracy, and could produce leg breaks, googlies, and top spinners, with no discernible change in his action. As well as his skill, O'Reilly was also known for his competitiveness, and bowled with the aggression of a paceman.
Following his retirement from playing, he became a well-respected cricket writer and broadcaster. According to Matthew Engel writing in Thirty Obituaries from Wisden, "When O'Reilly died, Sir Donald Bradman said he was the greatest bowler he had ever faced or watched."