Spock

Spock was a cat onboard.

Mascot
The mascot of the Spirit of Fire, Spock was allowed to be on the ship's command deck sometime in 2531.

Non-canon history
According to non-canonical blog posts by Halo Wars writer Graeme Devine, Spock was a female cat who was likely the pet of a crew member on the. She was apparently impregnated by another cat while onboard the ship.

Captain James Cutter thought that Spock and her pregnancy was a sign of good luck. Nurse Hershey had a feeling that Spock intended to give birth in her bed.

Trivia

 * Spock's name is a reference to the Vulcan Star Trek character of the same name.
 * Spock may also be a reference to Jonesy, another cat that lived on the.

List of appearances

 * Halo Wars