William Moses Kunstler (July 7, 1919 - September 4, 1995) was an American self-described "radical lawyer" and civil rights activist.

The son of a physician, Kunstler was born in New York City and educated at Yale College and Columbia University Law School. While in school, Kunstler was an avid poet, and represented Yale in the Glascock Prize competition at Mount Holyoke College.

Kunstler served in the U.S. Army during World War II in the Pacific theater, attaining the rank of Major, and received the Bronze Star. He was admitted to the bar in New York in 1948 and began practicing law. He was an associate professor of law at New York Law School (1950-1951).