George Arthren McIlwaine (c. 1905, South Africa – 31 October 1930, Calcutta, British India)[1] was a South African rugby union player and an early twentieth century rugby union international who is known as one of the "lost lions"[2] due to his participation on the 1927 British Lions tour to Argentina which, although retrospectively recognised as a Lions tour, did not confer test status on any of the four encounters with the Argentina national rugby union team.