Ian Reginald Thompson (born 16 October 1949) is an English long-distance runner, who gained success in marathon running.

Born in the town of Birkenhead, Cheshire (now Merseyside), Ian Thompson was regarded as just an ordinary club athlete and ranked 90th in Britain's 5,000 metres list at the time,[1] but suddenly broke through to world class as a marathon runner when asked to make up the numbers for his club, Luton United, in the Amateur Athletic Association of England (AAA) marathon championship on 27 October 1973.

He stayed with the leading group until the 20 kilometre mark and then steadily opening up a gap on the rest of the field[5] that stood at 98 seconds when he won in a time of 2:13:18.8.

Thompson's achievements were recognised in the 1974 SJA Annual Sports awards, where he was runner up to John Conteh in the Sportsmen of the Year category.

His wife Margaret was an early pioneer of marathon running for women in Britain and ran a British best time of 3:07:47 in Korso, Finland on 26 October 1975 and for a few months they held both the men and women's British marathon records, until Margaret's time was beaten by Christine Readdy (Kilkenny) in Feltham on 4 April 1976.