A personal assistant or aide was an assistant whose job it was to see to the needs and business of another individual.
Britt worked as the personal assistant to Christopher Brynner, owner of Brynner Information Systems, in 2024. She booked a room at the Clift on behalf of Brynner for Jadzia Dax, and also checked to see if any of Jadzia's friends was admitted to a city hospital or trauma ward, in September of that year. (DS9: "Past Tense, Part I")
Vash served as personal assistant to professor Samuel Estragon for five years before his death. (TNG: "Captain's Holiday")
Sakkath was Ambassador Sarek's personal assistant in 2366. (TNG: "Sarek")
Sabin Genestra served as an aide to Admiral Norah Satie in 2367. (TNG: "The Drumhead")
Cardassian Glinn's often served as aides to Guls. During his visit to the USS Enterprise-D in 2367, Gul Macet brought with him two aides, Glinn Daro and Glinn Telle. (TNG: "The Wounded") Two years later the Glinns Corak and Tajor were present alongside Gul Lemec during his negotiations aboard the Enterprise-D with Captain Edward Jellico in 2369. (TNG: "Chain Of Command, Part I") Gul Trepar's aide was a man named Glinn Borven. (DS9: "Ties of Blood and Water")
Starfleet Commander Wrightwell served as the aide to Vice Admiral Alynna Nechayev. In 2370, Captain Jean-Luc Picard consulted with Wrightwell, prior to a visit from the Admiral, to which Wrightwell expressed the Admiral's fondness for Bularian canapé. (TNG: "Journey's End")
After Seska defected over to the Kazon from USS Voyager, she took Teirna on as one of her aides. (VOY: "Basics, Part I")
Darok served as Martok's aide during the Dominion War, often giving the General more reports than he wished to see. (DS9: "Once More Unto the Breach")