Mathias Seger (born December 17, 1977) is a Swiss former professional ice hockey defenceman who played for the SC Rapperswil-Jona Lakers and the ZSC Lions of the National League (NL).
Seger began his professional career with SC Rapperswil-Jona in 1996.
He played three seasons with Rapperswil-Jona before joining the Lions in 1999.
With the Swiss men's national team he won a silver medal at the 2013 World Championships.
Seger also won the 2009 Champions League as well as six National League titles, all with the ZSC Lions.