William Willard Wirtz (March 14, 1912 – April 24, 2010) was a U.S. administrator, cabinet officer, attorney, and law professor.

He served as the Secretary of Labor between 1962 and 1969 under the administrations of Presidents John F. Kennedy and Lyndon B. Johnson.

He held the post of Labor Secretary throughout the Kennedy and Johnson administrations, during which time he is credited for having dealt effectively with the various trade union strikes of the 1960s.

While serving in the Labor Department, Wirtz developed programs for the Johnson administration's War on Poverty.

Wirtz wrote a memoir entitled "In the Rear View Mirror" which was published in 2008 by The Beloit College Press.