Admiral Leonard H. McCoy, MD was a male Human Starfleet officer of the 23rd and 24th centuries. He was an accomplished surgeon, physician, psychologist, and exobiologist, and was also considered an expert in space psychology. As chief medical officer, he served aboard the USS Enterprise and USS Enterprise-A for a combined twenty-seven years. (Star Trek: The Original Series; Star Trek II: The Wrath of Khan; Star Trek VI: The Undiscovered Country; TNG: "Encounter at Farpoint"; VOY: "Lifesigns", "Message in a Bottle")