Canon characters listed below are linked to the main article about them. Non-canon characters are not linked, but those that recurred, appearing or being mentioned in more than one story, are defined further in DC TOS volume 1 characters.
Enterprise-A navigator. Kirk orders Arex and Sulu to take the vessel to sector 9.
Ronald R. Penn
Starfleet cadet-commander who receives Captain Fields's order to take command of Cluster and the vessel's trainee crew. Even though the rank insignia drawn on Penn's uniform looks roughly like that of an ensign, he is addressed as both "cadet" and "commander" in dialogue, and apparently was in a position of authority over other lieutenants and lieutenant commanders on the bridge.
Romulan commander
Romulan starship commander who assaults the Cluster landing party, and then the vessel itself, after Penn's counter-attack. The same commander encountered during "The Doomsday Bug" storyline.
Kirk mentions that he just ditched a Federation "watchdog" assigned to Enterprise-A at their last stop.
Other characters
Fields
Captain of the USS Cluster. Fields led an ill-fated landing party that was massacred in a Romulan ambush.
Ventura
Starfleet cadet-lieutenant, a communications trainee assigned to USS Cluster. In some panels, Ventura's rank insignia is roughly drawn as a lieutenant junior grade, but in other clearers shots it is a full lieutenant's bar.
Bigelow
Starfleet lieutenant commander assigned to USS Cluster. Bigelow wore the yellow uniform patches of a pilot, and answered to orders Penn addressed to the helm, but Penn also addressed another female ensign as the "helmsman".
Marciari
Starfleet crewmember lost on the ill-fated USS Cluster landing party. It wasn't clear if the female on page one was named Testa, Marciari or McVey, but she must be one of those three.
McVey
Starfleet crewmember lost on the ill-fated USS Cluster landing party. It wasn't clear if the female on page one was named Testa, Marciari or McVey, but she must be one of those three.
Testa
Starfleet crewmember lost on the ill-fated USS Cluster landing party. It wasn't clear if the female on page one was named Testa, Marciari or McVey, but she must be one of those three.
Keller
Starfleet crewmember lost on the ill-fated USS Cluster landing party.
"Spitz" Spithogiannis
Starfleet crewmember lost on the ill-fated USS Cluster landing party.
Blonde female ensign, with gray uniform patches, assigned to the helm on USS Cluster. Since she wore gray insignia, it would seem she specialized as a navigator, despite being referred to as "helmsman" -- or she could have been filling both roles. Mr. Bigelow also responded to orders.
Andorian ensign
Andorian Starfleet ensign, with yellow uniform patches, assigned to USS Cluster. His uniform indicates he was probably an engineer, since he was not holding a pilot position -- yellow uniform insignia denote pilots or engineers.
