William H. Gerstenmaier (born September 28, 1954) is an aerospace engineer and policymaker who is the Vice President of Build and Flight Reliability at SpaceX.

[6] He had early dreams of being a test pilot, and after high school, enrolled at the United States Naval Academy.

During his time at Purdue, Gerstenmaier found a great interest in spaceflight technology, and chose to focus on this area for his career.

Initially doing research with supersonic wind tunnels, developing air data curve information used during entry on the Space Shuttle.

Gerstenmaier's time with the ISS team, came as the first crews began to occupy the station and the US Orbital Segment was under heavy construction.

"[10] He would oversee the Commercial Crew Program that would see NASA pivot from the traditional model of government-owned and operated spacecraft, to one where the agency would act as a customer, purchasing flights as needed.

In one particularly critical decision, Gerstenmaier pushed back when Boeing had lobbied NASA for a sole-source contract, arguing that it needed the Commercial Crew Program's full budget to develop its Starliner capsule.

The multi-year Commercial Crew Program had been designed to foster competition and redundancy, and Gerstenmaier believed that selecting just one company would undermine these goals.

[8][14][15] SpaceX hired Gerstenmaier away from NASA in February 2020 in what was originally announced as a role as a consultant to Hans Koenigsmann, the company's vice president of mission assurance.

[16][3][17] When Koenigsmann announced he was retiring in February 2021, SpaceX said that Gerstenmaier had agreed to join the company as its Vice President of Build and Flight Reliability.