A is for Admiral Archer's prized beagle, Athos. Descendant of Porthos. His wherabouts and condition are unknown.
B is for Beta Niobe, the star that went supernova and destroyed the planet Sarpeidon
C is for Classified. The Corbomite device is.
D is for Deneva, home of Sam and Aurelan Kirk.
E is for Excelsior. She's supposed to have trans-warp drive.
F is for Fesarius, Balok's ship in "The Corbomite Maneuver"