An admiral who warned Picard of a conspiracy within Starfleet and later fell victim to the parasitic aliens behind it.
Admiral Gregory Quinn was an old friend of Jean-Luc Picard. In Coming of Age he offered Picard a promotion and secretly ordered an inspection of the Enterprise-D, telling Picard he suspected that something was wrong within Starfleet Command and needed officers he could trust.
In Conspiracy his fears proved justified, but by then he had been taken over by a parasitic alien. Quinn attacked Riker and Geordi with unusual strength before Dr. Crusher stunned him. After the creatures were destroyed, Quinn recovered.