Peder Otto Onstad (June 4, 1874 – March 17, 1961) was an American educator and politician who served as a member of the Wisconsin State Assembly.

[1] He was one of ten children born to Johannes (John) Christensen Onstad and his wife Anna Lee.

His maternal grandfather Erik Lee was a supporter of the Haugean movement and left Norway following religious persecution, becoming the first settler in the Christiana area.

[3] His brother Erick J. Onstad served as an attorney and was deputy state treasurer of Wisconsin underneath Solomon Levitan in the 1920s.

[1] In 1909, Onstad was elected to represent Dane County in the Wisconsin State Assembly as a member of the Republican Party.