Conrad Louis Wirth (December 1, 1899 – July 25, 1993) was an American landscape architect, conservationist, and park service administrator.

With the coming of the New Deal he supervised the service's Civilian Conservation Corps (CCC) program in the state parks.

Wirth's crowning achievement was Mission 66, a 10-year, billion-dollar program to upgrade park facilities and services by the 50th anniversary of the NPS in 1966.

Wirth submitted his resignation to President John F. Kennedy in the fall of 1963 and left the directorship in early 1964, after recommending George B. Hartzog Jr. as his successor.

A member of the National Geographic Society's Board of Trustees, he was also active in conservation and Park Service alumni affairs.