Joachim Thomassen (born 4 May 1988) is a former Norwegian footballer.
Thomassen started his youth career with Sarpsborg FK before joining Sparta Sarpsborg in 2007. In January 2008, he joined Fredrikstad and played his first game for the club against Kongsvinger. In May 2009, he signed a contract extension for Fredrikstad until 2012. In November 2011, he was rumored to join the Seattle Sounders FC of Major League Soccer. Before the 2012 season, he signed a contract with VÃÂ¥lerenga. After two seasons with VÃÂ¥lerenga he signed for Sarpsborg 08 FF ahead of the 2014 season.
Thomassen has played for the Norway national under-17 football team, Under-19 team, and Under -21 team.