A is for the Alpha Cygnus star system.
B is for Bajoran Buggerers.
C is for Ceti Alpha 5. "Nuke it from orbit. Only way to be sure." Is what they should have done.
D is for Deltan pheromones.
E is for Elasian tears, which also contained some very powerful pheromones.
F is for Ferengi Rules of Acquisition. Something they just made up to sound clever.
G is for Gorn eyes. They were silver in color and compound in nature in our universe and appeared to be more reptillian-looking in the Mirror Universe.
H is for humpback whales. Not people.
I is for Intrepid. Her destruction caused a great disturbance in the force.
J is for Joanna McCoy. She never appeared on TOS nor in any of the films so technically she's isn't canon, but a lot of fans over the years have considered her to be.
K is for Klingon Mythology.
L is for Leandra, the first name of Dr. Tolian Soran's late wife who died when the Borg destroyed the El-Aurian homeworld.
M is for Mintakans. Neanderthal Vulcans.
O is for Ohniaka III, location of a Federation outpost attacked by renegade Borg drones led by the android Lore.