Mattias is a masculine given name found most prominently in Northern Europe. It is a cognate of Matthew and Matthias, and may refer to:
In sports:
- Mattias Bjärsmyr, Swedish football defender
- Mattias Ekström, racing driver from Sweden
- Mattias Eriksson, athlete from Sweden
- Mattias Norström, Swedish defenceman for Los Angeles Kings of the National Hockey League
- Mattias Öhlund, Swedish defenceman for Vancouver Canucks of the National Hockey League
- Mattias Tedenby, Swedish ice hockey player who currently plays for HV71 of the Swedish Elitserien
- Mattias Weinhandl, Swedish ice hockey player
In other fields:
- Mattias Eklundh, the lead guitarist and vocalist of Swedish power trio Freak Kitchen
- Mattias Flink, Swedish mass murderer
- Mattias Gardell, Swedish scholar of comparative religion
- Mattias Klum, Swedish photographer