A prefect is an administrative official in several cultures, often placed in a supervisory position over a district, planet, or sector.
Jaris was the Prefect of Argelius II in 2267. (TOS: "Wolf in the Fold")
Dukat was the Prefect of Bajor to the Cardassian Union during the occupation of that world. (DS9: "Emissary")
While participating in a ruse to gain access to the Hutet labor camp on Cardassia IV, Miles O'Brien claimed that Kira Nerys had an appointment with the resident prefect. (DS9: "The Homecoming")