Eulus is a class M planetoid orbiting a G class yellow star. It is located near the Klingon Empire in a neutral sector of the Organian Treaty Zone in the galaxy's Beta Quadrant. It is the homeworld of the developing Eulus natives.
Eulus has at least two large continents and oceans. Terrain is barren with mountains spotted with cactus. Lifeforms include snakes and pine trees. Eulus has notable deposits of dilithium and appears orange from orbit. It is sparsely populated.
In 2267, a Klingon commander purchased exclusive dilithium mining rights to Eulus, signed by treaty with the Grand Qaal of Eulus. The Klingons departed with a sample case of dilithium, unaware that they were being conned with cheap synthetic dilithium by Harry Mudd. After uncovering the fraud, James T. Kirk and Spock attempted to recover the unstable crystals before they destroyed the Klingon battle cruiser IKS Ectacus and incited a war. (TOS comic: "Operation Con Game")