Robert Noonan (17 April 1870 – 3 February 1911), born Robert Croker and best known by the pen name Robert Tressell, was an Irish writer best known for his novel The Ragged-Trousered Philanthropists. Tressell spent his entire early adult working life in South Africa. It was in Johannesburg that he was drawn into labour organisation and socialist politics. In Johannesburg, he was also involved with some of the leading protagonists of Irish nationalism.