Doctor Riley Frazier was a Human female of Texan descent, and was particularly fond of her mother's famous Texas barbecue. Her favorite flower was the bluebonnet, which she had picked together with her grandfather when she was a child.

As an adult, Frazier joined Starfleet where she became an officer, serving aboard the Federation starship USS Roosevelt during the mid 2360s.

In early 2367, Frazier, who was at that time a science officer, was aboard the Roosevelt when the ship participated in the Battle of Wolf 359. Frazier was among at least four crewmembers of the Roosevelt assimilated by the Borg during the battle and transported back to the Delta Quadrant.

The Borg cube that Frazier was on was disabled by an electrokinetic storm in 2368 and its link to the hive mind was severed. Frazier and the others who survived retrieved their pre-assimilation personalities and settled on a nearby M-class planet. When the former drones from different species began to attack each other, Frazier, her friend Orum, and others founded the Cooperative. Orum produced a prothestic arm for Riley to replace her Borg-prosthesis. Over the years she considered the members of the Cooperative as her new family. Frazier set up a Federation distress call to get outside help such as security upgrades, medical supplies and some weapons.

Her signal was finally answered by Chakotay and Ensign Kaplan in 2373, who landed on the planet. Kaplan was killed and Chakotay so severely injured by a rival faction, that he was linked to Frazier and others in an attempt to heal his wounds.

After establishing contact with the USS Voyager, Frazier wished to get Voyager's assistance in re-activating the neuroelectric field generator on the disabled Borg cube in order to stop the fighting and reestablish order. Captain Janeway refused, fearing a new collective.

Despite her rejection, Frazier used the Cooperative's former link with Chakotay to force him to go to the disabled cube and re-activate the generator, which he did. When the link was established, Frazier and the Cooperative was able to restore order and she ended the neural link with Chakotay. (VOY: "Unity")

Riley Frazier was played by Lori Hallier. Riley as a child was played by an unknown actress.