A is for Alaska. William Riker was born and raised there.
B is for Betazoid Boobies.
C is for Capella IV. In the Prime timeline Leonard McCoy was assigned there before he joined the crew of the Enterprise 1701.
D is for Delta Vega. Captain Kirk attempted to maroon Gary Mitchell there.
E is for the Excelsior, a cutting edge starship launched in 2285 and one which may have still been in service as late as 2370 if some dialogue in TNG is to be considered.
F is for Farpoint Station. Which was actually a giant shape-shifting space jellyfish.
G is for Gorn. Earth humans first heard about them in the 2150s and continued to have violent encounters with the species over a hundred years later.
H is for Holodiction. Which Reg Barclay suffered from.
I is for Iconian Empire.
J is for Jarok. Romulan defector.
K is for Kara, leader of the Eyemorg women of planet Sigma Draconis VI.
L is for Lore. Data's evil twin.
M is for Merikus, the name taken by Beagle captain R.M. Merrick after he took refuge on planet 892-IV and assimilated into that world's Roman-style society.
N is for Number One. Captain Picard's nickname for Willy Riker.
O is for Orion Syndicate, one of the great commercial and criminal organizations of the 22nd through 24th centuries.