A piano player, more formally known as a pianist, was a musician who played the piano.
In 2374, Vic Fontaine invited Odo to fill in at the piano, as his piano player had made a killing at the craps table and had left for Reno. (DS9: "His Way")
Claude was the pianist of "Le Coeur de Lion" who accompanied Mademoiselle de Neuf on the piano. (VOY: "The Killing Game")
External link Edit