Gregory Quinn

Rear Admiral Gregory Quinn was a high ranking Starfleet official attached to Starfleet Command in the 2360s.

Quinn played a crucial role in the uncovering of an attempt to take over Starfleet Command by neural parasites in 2364. Quinn ordered Inspector General officer Dexter Remmick to investigate whether or not the USS Enterprise-D had been infiltrated also. (TNG: "Coming of Age")

Nothing was discovered at the time, but Quinn himself would later become a victim of alien infestation. His mind was overtaken by the unknown alien intelligence in an attempt to infiltrate Starfleet Headquarters in 2364. Captain Jean-Luc Picard and Commander William Riker of the USS Enterprise-D, later that year, destroyed the alien mother creature, which housed in the body of Dexter Remmick, thereby also killing all other alien parasites on Earth, freeing Quinn from alien infiltration. (TNG: "Conspiracy")

Admiral Quinn was played by Ward Costello. His rank insignia was an admiral braid with no pip, indicating the lower half of rear admiral, in the TNG Season one rank insignia. His rank during TOS era would have been equivalant to commodore.