Christopher John "Chris" Cassidy (born January 4, 1970) is a retired NASA astronaut and United States Navy SEAL.

His specializations in military tactics include long range special reconnaissance (vehicular and foot patrols), direct action building assaults, non-compliant ship-boardings, desert reconnaissance patrols, combat diving, underwater explosives, and a variety of air operations, including parachuting, fast roping, and rappelling.

He accumulated over 200 hours underwater as pilot, navigator, or mission commander of a two-man flooded submersible SDV, which is launched and recovered from a host-ship submarine.

Cassidy volunteered for and completed a week-long, 180-mile (290 km) charity kayak paddle from Norfolk, Virginia to Washington, D.C. to raise money and awareness for the Special Operations Warrior Foundation.

[4] The seven astronauts docked with the ISS on July 17, joining the six-person Expedition 20 crew commanded by Russian cosmonaut Gennady Padalka.

[7] Cassidy's third spacewalk marked the completion of the Japanese Experiment Module, a feat that took three space shuttle missions starting with STS-123.

[8] Cassidy was assigned to the Expedition 35 crew as a flight engineer and flew to the ISS aboard Soyuz TMA-08M (US designation: 34S), which launched on March 28, 2013.

[2][9] On May 11, 2013, Cassidy and Thomas Marshburn performed an unplanned spacewalk to replace a pump controller box suspected to be the source of an ammonia coolant leak.

[15] On June 2, 2017, Cassidy was replaced by Patrick G. Forrester as Chief of the Astronaut Office and was returned to normal flight status.

He was the ISS commander for Expedition 63, which consisted of Cassidy and Russian cosmonauts Ivan Vagner and Anatoli Ivanishin.

[16][17] Cassidy was joined by fellow NASA astronauts Doug Hurley and Bob Behnken on May 31, 2020, with the docking of Crew Dragon Demo-2.

[18] Cassidy joined the National Medal of Honor Museum Foundation as President and CEO in August 2021[19] after retiring from the Navy and the NASA Astronaut Corps earlier that year.

Recreational interests include traveling, biking, camping, snow skiing, weight lifting, running, basketball, real estate, and home improvement.