Administrator is a title given to the executive leader of an organization.
In the 14th century, the village of Ressik on Kataan was ruled by an administrator. (TNG: "The Inner Light")
In 2154, V'Las held the title of Administrator in the Vulcan High Command. In that role, he appeared to have wide-ranging power over both civilian and military matters. (ENT: "Kir'Shara")
In 2266, Dr. Tristan Adams was the administrator of the Tantalus Penal Colony. (TOS: "Dagger of the Mind")
In 2267, Mr. Hengist of Rigel IV, was made Chief Administrator of the capital city on Argelius II, just prior to the discovery that he was possessed by Redjac. (TOS: "Wolf in the Fold")
In 2269, Plasus was the administrator of the cloud city of Stratos on Ardana. As such, he was leader of the planet's government. (TOS: "The Cloud Minders")
In 2369, Orton was the administrator of Arkaria Base, and used his position to lead a group of terrorists to steal trilithium from the USS Enterprise-D. (TNG: "Starship Mine")
In 2371, Rom was made Senior Administrator of the Ferengi Benevolent Association by Grand Nagus Zek, when Zek was influenced by the Prophets. (DS9: "Prophet Motive")
From 2373-2375, Weyoun held the position of Administrator of the Alpha Quadrant for the Dominion. (DS9: "Call to Arms")
In 2377, Chellick was the administrator of Hospital Ship 4-2 on Dinaal. He was responsible for allocating medical care, and used a special computer program to do it. (VOY: "Critical Care")