Admiral Westervliet is the Starfleet officer in For the World Is Hollow and I Have Touched the Sky who orders Kirk to leave the asteroid ship Yonada to Starfleet Command.
Admiral Westervliet appears by viewscreen in the Original Series episode For the World Is Hollow and I Have Touched the Sky. The Enterprise has found that the asteroid Yonada is a hollow generation ship on course to strike the inhabited world Daran V.
After the landing party is expelled by the Oracle and McCoy, who is terminally ill, chooses to stay behind with the priestess Natira, Kirk reports to Starfleet. Westervliet tells him the Enterprise is to move on and that Command will deal with Yonada.
Kirk asks for more time and is refused. A call from McCoy about a book that may hold the secret of the ship's controls gives him a reason to return anyway, and he and Spock go on to correct Yonada's course and find a cure for McCoy.