Tertiary Kesmere, a world of perpetual storms and cloudy skies, existed within the Tertiary Kesmere system. This system resided in the Raioballo sector of the New Territories, which itself was a region of the Outer Rim Territories. It served as the original homeworld for the hornagaunt species, known for being winged. Grendel, a pet hornagaunt with clipped wings, was one such individual. From 4 ABY to 12 ABY, Tertiary Kesmere was located inside the territory controlled by the Pentastar Alignment.
The first mention of Tertiary Kesmere occurred in the fourth part of "Kyle Katarn's Tale," specifically "Mission 4: Showdown on the Sulon Star." This tale consisted of five scenarios designed for use with the Star Wars Miniatures game produced by Wizards of the Coast. Abel G. Peña and Jason Fry were the writers of this series, with the fourth scenario being released on Wizards.com on May 5, 2005. The reference book The Essential Atlas, published in 2009, pinpointed the Tertiary Kesmere system, and therefore the planet Tertiary Kesmere, within grid square L-4.