Sir Michael Francis Atiyah OM PRS FRSE FMedSci FAA FREng (/əˈtiːə/; 22 April 1929 – 11 January 2019) was a British-Lebanese mathematician specialising in geometry. His contributions include the Atiyah–Singer index theorem and co-founding topological K-theory. He was awarded the Fields Medal in 1966 and the Abel Prize in 2004.