Watley is a lieutenant aboard Kirk's Enterprise in 2268 who flirts with the time-travelling Julian Bashir, prompting him to wonder whether she is his own great-grandmother.
Lieutenant Watley appears in the fifth-season episode Trials and Tribble-ations, played by Deirdre Imershein. She serves on the original USS Enterprise during its visit to Deep Space Station K-7, when the crew of the Defiant are aboard in period uniform hunting for Arne Darvin's bomb.
She takes an interest in Bashir, who is posing as a member of the crew. Bashir then remembers that his great-grandmother was named Watley and that nobody in the family ever knew who his great-grandfather was, and he begins to worry aloud that he may be caught in a predestination paradox.
Miles O'Brien refuses to take the idea seriously, and the mission ends without Bashir putting it to the test.