Mark Ashton Richardson (born 26 July 1972 in Slough) is a British former athlete who competed mainly in the 400 metres.
He competed for Great Britain in the 1996 Summer Olympics held in Atlanta, United States in the 4 x 400 metre relay where he won the silver medal with his team mates Iwan Thomas, Jamie Baulch and Roger Black.
This team set a UK record, 2:56.60, in the process.
At the 1997 World Championships in Athens, Richardson ran the anchor leg for Great Britain in the 4 × 400 m relay, winning the silver medal.
His unofficial split time was 43.5.
On 7 January 2010 it was announced that Great Britain's 1997 World Championship 4 × 400 m relay team are to be awarded the gold medal; they were beaten by a U.S.
team that included Antonio Pettigrew, who admitted in 2008 to using performance-enhancing drugs.