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

Mattias Claesson
Medal record
Representing  Sweden
Men's athletics
European Indoor Championships
Bronze medal – third place 2009 Torino 800 m

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.

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