Marcus Klingenberg Mathisen

Marcus Klingenberg Mathisen's career began at FC Copenhagen, where he joined the first team in July 2015. He made four league appearances that season as the club won the Danish Superliga and the Danish Cup, and he had earlier been part of the squad for the 2014–15 Danish Cup final, though he stayed on the bench that day.

A move to Sweden followed in August 2016, when Mathisen joined Halmstads BK. His time there produced the standout moment of his career: in November 2016, in the promotion playoff final against Helsingborgs IF, he scored twice to help secure Halmstads' return to the Allsvenskan for the 2017 season. He went on to make 67 league appearances for the club, scoring six goals, before signing for Falkenbergs FF on a free transfer in January 2019, where he added 43 league appearances and three goals.

In June 2023, Mathisen moved to Germany, joining SV Wehen Wiesbaden in the 2. Bundesliga, where he made 31 league appearances. A year later, in June 2024, he signed for 1. FC Magdeburg after a release clause in his Wehen Wiesbaden contract was triggered; the fee has been reported at around €1.4 million, though other reports describe it only as an undisclosed sum in the six figures. He has since made 63 league appearances for Magdeburg.

At youth international level, Mathisen represented Denmark from under-16 through under-19 level between 2012 and 2015, collecting caps across all four age groups, but he has not been capped by the senior national team.