Tressaurian

Tressaurians were a Gorn-like species whose relations with the Federation in the 23rd century were hostile at best. (Starship Exeter: "The Tressaurian Intersection")

Physiology
Tressaurians were bipedal and reptilian in appearance, with a thick, scaled epidermis, horns, a stiff neck frill, and clawed hands.

They had considerable physical strength.

Civilization
To outside cultures Tressaurians presented a militaristic front, brusquely ordering trespassers to leave their claimed territory and firing upon other ships with little or no warning. The Federation considered them to have little interest in pure science or technology other than weaponry.

Trengaro Incident
Their most significant encounter with the United Federation of Planets as of 2269 was when a Tressaurian ship fired on an unarmed transport containing amongst other passengers then-cadet John Garrovick; the survivors ended up stranded on the uncharted planet Tengaro for four years.

Tholian Incident
Tressaurian space had a border near the planet Corinth IV and Starbase 16: there were a dozen colonies and forwards military bases in that sector. In 2269, Tholians built a gigantic gravity device that would translate a huge swathe of Tressaurian territory in to a different dimension, and devastate a huge volume of space. Tressaurians stole a smaller prototype and tested it on Corinth IV, destroying Starbase 16 and much of the planet, killing thousands of people. The USS Kongo and USS Exeter (NCC-1706) intervened, seizing the prototype and, despite repeated attacks from Tressaurian warships, using it to destroy the larger device, effectively saving 20 million Tressaurians from destruction. The Tressaurians responded by breaking off their attacks without comment.