Galactica

Galactica is an Autobot from the Generation 1 continuity family.

You can't see me!

_{This character has no official visual representation in any Transformers product or media... yet, at least.}

Galactica was one of the many casualties of the war for Cybertron before the launch of the Ark.

Fiction

Dreamwave comics continuity

The Decepticons Frenzy and Rumble mention Galactica as one of the various Autobot casualties while enjoying some downtime, getting to the "G"s in tallying up the known dead. The Age of Wrath issue 3

Trivia

• It is possible that due to the name ending in "a", that Galactica was a female Transformer, but since nothing more than a name is known about this individual, it is conjecture at best.
  
  
  From Teletraan I: The Transformers Wiki, a Wikia wiki.