In *Star Trek: The Original Series*, the ship’s chief medical officer is Leonard McCoy.
McCoy serves aboard the USS Enterprise under Captain James T. Kirk and is commonly called “Bones.” He is a skilled physician with a forceful, sometimes irritable personality, and his medical judgment often provides a humanist counterpoint to Spock’s logic.
The character was played by DeForest Kelley throughout the original series and its six films. McCoy’s friendship with Kirk is one of the Enterprise crew’s central relationships, while his arguments with Spock create the show’s familiar balance of emotion, reason, and command.
A common mix-up is choosing Beverly Crusher, who is the chief medical officer on the USS Enterprise-D in *Star Trek: The Next Generation*. Julian Bashir belongs to *Deep Space Nine*, and Phlox serves aboard the NX-01 Enterprise in *Star Trek: Enterprise*. McCoy also appears as an older admiral in *The Next Generation*’s pilot episode.