A dockmaster was the person responsible for the starship docking procedures of a facility.
In 2152, a Markalian served as the dock master of the outpost located on Pernaia Prime's moon. His duties included maintaining the landing deck; he also verified T'Pol's warrant for Menos' arrest. (ENT: "The Seventh")
In 2293, Captain James T. Kirk asked Commander Uhura to hail the dockmaster, so the USS Enterprise-A could depart from spacedock. This dockmaster operated from the dock's control tower. (Star Trek VI: The Undiscovered Country)
In a deleted scene of "Broken Bow", a Markalian dockmaster informed Captain Jonathan Archer and Sub-Commander T'Pol that a Klingon K'toch-class scout ship had visited his trade outpost on Rigel X seven days beforehand. While in his control tower, this dockmaster monitored the approach vector of Elkan Nine.