Ivar Mathisen (14 June 1920 – 7 October 2008) was a Norwegian sprint canoeist who competed in the 1940s and early 1950s.

He received a silver medal in the K-2 10000 m event at the 1948 Summer Olympics in London with Knut Østby.

[1] During the German occupation of Norway, which started before Mathisen's twentieth birthday, the club was dissolved, but several members continued training.

[3] He competed in the 1948 ICF Canoe Sprint World Championships, and received a silver medal in K-1 4 x 500 metres relay, together with teammates Ivar Iversen, Hans Martin Gulbrandsen and Eivind Skabo.

[4] Before the 1948 Summer Olympics, Mathisen and his teammate Knut Østby (also from Bærum) were considered as having the highest medal hopes in the Norwegian canoeing squad.