Harry J. Mortensen (September 18, 1876 – July 24, 1970) was a member of the Wisconsin State Assembly.

Mortensen was born on September 18, 1876, in Fountain, Wisconsin.

[1] He graduated from what is now the University of Wisconsin-Stevens Point in 1898 and the University of Wisconsin Law School in 1902.

He was married to Carolyn Balgord from 1906 until her death in 1953.

Additionally, he was City Attorney of New Lisbon, District Attorney of Juneau County, Wisconsin, and the Wisconsin Commissioner of Insurance.