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

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.

He advocated for remedial education for school dropouts and for retraining programs for unemployed workers.

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