A is for Acamar III, the home world that the Gatherers left.
B is for Benny Russell, the 20th century black science fiction writer that the Wormhole Prophets caused Benjamin Sisko to imagine that he was.
C is for corbomite, an imaginary substance that makes the Enterprise invincible.
D is for Dathon, captain of the Tamarian ship encountered by the Enterprise-D in early 2368.
E is for Esteban, the captain of the Grissom who got his ship blown up in one shot.