Ryan was a human who lived in the 23rd century. She served Starfleet as a lieutenant.

In 2273, Lieutenant Ryan had recently been assigned to the USS Enterprise (NCC-1701). She filled in for Lieutenant Commander Hikaru Sulu as helm officer when he was sent into Japan's past by the omnipotent being Weyland. Ryan warned Captain James T. Kirk that the Enterprise's orbit around Cragon V was beginning to decay, and detected the Klingons Kral and Vladra on sensors when they had been ejected from an airlock of the IKS Ghargh. (TOS novel: Home is the Hunter)

USS Enterprise (NCC-1701) flight control personnel
Under Robert April FerarraC. FloridaNobisPoI. Soulian Under Christopher Pike MohindasNumber OneJ. TylerVincentB. Wayne UFP 2260s seal Enterprise cmd insignia
Under James T. Kirk (first five-year mission) AkrumbaD. AldenArex N. E.D. BaileyT. BarrowsBrubakerP. ChekovM. CheungConnorsS. DePaulV. DeSalleJ. FarrellFrostGreenB. HadleyB. HansenHarrisonL. KelsoS. KerbyJ. KyleR. LatimerR. LeslieV. MahtaniG. MitchellM. RahdaK. RileySanchezShafferSpinelliJ. StilesH. SuluVitaliD. Walking Bear
Subsequent missions under Kirk & Spock N. BryceP. Chekovde BroekM. DiFalcoDomenickM. LedouxHaarvHwavirëA. LeeSaavikIliaE. SherwoodRyanH. SuluT'Lara UFP 2271 seal Enterprise 2270s gold insignia
see also: administrative personnelcommunications personnelengineering personnelmedical personnelsecurity & tactical personnelsciences personnelsenior staffunnamed