Mattias Claesson

Mattias Claesson (born 26 July 1986) is a Swedish male middle-distance runner who specializes in the 800 metres.

He finished fourth in the 4 × 400 metres relay at the 2006 IAAF World Indoor Championships, with teammates Joni Jaako, Johan Wissman and Andreas Mokdasi. In the 800 metres' distance he won the 2005 European Junior Championships and finished fifth at the 2007 European Athletics Indoor Championships.

His personal best time is 1:46.46 minutes, achieved in June 2006 in Karlskrona.