A young Enterprise officer played by Jim Goodwin who serves as navigator in the early first-season episodes The Enemy Within and Mudd's Women and takes the communications station in Miri.
Lieutenant John Farrell is one of several officers who occupy the navigator's seat beside Sulu in the first season of the original series, before the post settled on a regular character. He was played by Jim Goodwin.
He is at navigation in The Enemy Within, during the transporter accident that splits Kirk in two, and again in Mudd's Women, where like most of the men aboard he is captivated by Harry Mudd's three passengers.
His third and last appearance is in Miri, in which he remains on the ship as relief communications officer while the landing party is trapped on the planet below.