Eric Hasslein was a Starfleet officer in the 24th century who had risen to the rank of Admiral. Hasslein was the director of Starfleet's exploration and colonization division.
In 2382, Admiral Hasslein announced his retirement from Starfleet. Captain Jean-Luc Picard was briefly considered to replace him. (TNG - Typhon Pact novel: Paths of Disharmony)