Ham (July 1957 – January 19, 1983), a chimpanzee also known as Ham the Chimp and Ham the Astrochimp, was the first ape launched into space. On January 31, 1961, Ham flew a suborbital flight on the Mercury-Redstone 2 mission, part of the U.S. space program's Project Mercury.

Ham was known as "No. 65" before he safely returned to Earth, when he was named after an acronym for the laboratory that prepared him for his historic mission—the Holloman Aerospace Medical Center, located at Holloman Air Force Base in New Mexico, southwest of Alamogordo. His name was also in honor of the commander of Holloman Aeromedical Laboratory, Lieutenant Colonel Hamilton "Ham" Blackshear.

Ham was born in the wild in French Cameroon, his birth month retrospectively calculated as July 1957 based on dental eruption. He was captured by animal trappers and sent to the Rare Bird Farm in Miami, Florida. He was purchased by the United States Air Force and brought to Holloman Air Force Base in July 1959. Ham was sold to the United States Air Force for $457.

There were originally 40 chimpanzee flight candidates at Holloman. After evaluation, the number of candidates was reduced to 18, then to six, including Ham. Officially, Ham was known as No. 65 before his flight, and only renamed "Ham" upon his successful return to Earth. This was reportedly because officials did not want the bad press that would come from the death of a named chimpanzee if the mission were a failure. Among his handlers, No. 65 had been known as "Chop Chop Chang".

Beginning in July 1959, the two-year-old chimpanzee was trained under the direction of neuroscientist Joseph V. Brady at Holloman Air Force Base Aero-Medical Field Laboratory to do simple, timed tasks in response to electric lights and sounds. During his pre-flight training, Ham was taught to push a lever within five seconds of seeing a flashing blue light; failure to do so resulted in an application of a light electric shock to the soles of his feet, while a correct response earned him a banana pellet. Ham was trained for 219 hours during a 15-month period.

While Ham was the first great ape, he was not the first animal to go to space; there were many other types of animals, including primates, that had left Earth's atmosphere before him. However, none of these other animals could provide the significant insight that Ham could provide. One of the reasons that a chimpanzee was chosen for this mission was because of their many similarities to humans, including similar organ placement inside the body and having a response time to a stimulus that was very near to that of humans. Through observing of Ham scientists would gain a better understanding of the possibility of sending humans into space.

On January 31, 1961, Ham was secured in a Project Mercury mission designated MR-2 and launched from Cape Canaveral, Florida, on a suborbital flight.

A number of physiological sensors were used to monitor Ham's vital signs (electrocardiogram, respiration, and body temperature). A commercial rectal thermistor probe was used instead of the probe used on the human Mercury astronauts. The probe was inserted 8 inches deep into Ham's rectum. The physiological sensors were placed on Ham about 10 hours before liftoff. Ham's ability to complete tasks during the flight were assessed by the psychomotor apparatus. The apparatus gave Ham a visual cue in the form of colored lights and required a response from two levers; if he succeed in his task, drink and food pellet would be awarded; failure would be punished by a shock to the soles of his feet.