Mathias Seger 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. He was inducted into the IIHF Hall of Fame in 2020.

The Switzerland men's national ice hockey team is a founding member of the International Ice Hockey Federation (IIHF) and is controlled by the Swiss Ice Hockey Federation.