Date of Birth: 
About 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.
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