Andrew Russell Forsyth FRS (18 June 1858, Glasgow – 2 June 1942, South Kensington) was a British mathematician.Forsyth studied at Liverpool College and was tutored by Richard Pendlebury before entering Trinity College, Cambridge, graduating senior wrangler in 1881. He was elected a fellow of Trinity and then appointed to the chair of mathematics at the University of Liverpool at the age of 24.