Ryan was a human who lived in the 23rd century. In the early 2270s he served Starfleet as captain of the USS Lafayette.

On stardate 6352.4, Captain Ryan and three members of his crew were stranded on the planet Andronicus due to a transporter malfunction. All four members of the landing party were killed by the effects of Berthold radiation from the planet's star. Captain James T. Kirk and the senior staff of the USS Enterprise later reviewed Ryan's final log in preparation for a mission to Andronicus. (TOS comic: "... Like a Woman Scorned!")