Isaac Pigeon Walker (November 2, 1815 - March 29, 1872) was an American politician who served as a U.S. Senator from Wisconsin.
Walker was born in Virginia and moved with his family to Illinois in 1825. He practiced law in Springfield, Illinois, and served one term in the Illinois House of Representatives. He moved to Wisconsin in 1841 and practiced law in the Milwaukee area. He served in Wisconsin's territorial legislature from 1847 to 1848. When Wisconsin was admitted as a state in 1848, Walker was elected as a Democrat to represent Wisconsin in the United States Senate, where he served until 1855.
He is buried at Forest Home Cemetery in Milwaukee.
Isaac Walker's older brother, George H. Walker, was a founder and mayor of Milwaukee, Wisconsin.
Preceded by: none U.S. Senator (Class 3) from Wisconsin 1848-1855 Succeeded by: Charles Durkee