Paul Ansel Chadbourne (October 21, 1823 – February 23, 1883) was an American educator and naturalist who served as President of University of Wisconsin from 1867 to 1870, and President of Williams College from 1872 until his resignation in 1881. He was also the second President of the Massachusetts Agricultural College (later University of Massachusetts) in 1867 and again from 1882 until his death in 1883.