Hartvig Nissen (1857 – February 4, 1924) was a Norwegian gymnast primarily active in Norway and the USA.

His father, Ole Hartvig Nissen, was the owner and principal of a small private school.

An eye injury suffered during a childhood snowball fight prevented him from entering military school.

In March 1883 he moved to Washington, D.C., where he visited the German Gymnastics Club a few days after arriving.

In September 1883, he rented a three-story building at 903 16th street, two blocks from the White House, and named it "The Swedish Health Institute".