Peter C. Theisinger was project manager of NASA's Mars Exploration Rover Mission.

Originally from Fresno, California, Theisinger graduated from the California Institute of Technology in 1967 with a bachelors degree in physics. He joined NASA's Jet Propulsion Laboratory as payload integration engineer that year and except for a three-year span in the early 1980s has worked at JPL since. Among the missions on which he has participated were the 1967 Mariner 5 flyby mission to Venus, the 1971 Mariner 9 orbiter mission to Mars, the Voyager mission to the outer planets of the solar system, the Galileo mission to Jupiter, and the Mars Global Surveyor orbiter.

Theisinger is currently project manager for the 2009 Mars Science Laboratory mission.