The Locrix are described by Val-Yor as "vicious killing machines" whose goals are to achieve total dominion over the galaxy. They are a mechanical race of extraterrestrials that use advanced weapons such as lasers to defeat enemies.
Their first appearance was in the episode "Troq", where the galactic hero Val-Yor arrives on Earth to fight off a group of invading Locrix. Val-Yor recruits the Teen Titans and has them all attack the Locrix. He does not allow Starfire to participate, and constantly ignores her, due to a prejudice he has against Tamaraneans, a race which Val-Yor considers weak. However, Starfire ignores orders and still participates in the battle, also venturing with him into the home planet of the Locrix. Together, the two of them set up a Quantum Eradicator on the planet, which subsequently destroys all of the Locrix on the planet.
- Given Val-Yor's known racism against Tamaraneans, and the very little information that is known about the Locrix, it is possible that the Locrix are not, in fact, the world-destroying conquerers Val-Yor paints them to be and are instead further targets of his racism. It is equally possible that the Locrix truly are a malevolent race, however.
- The Locrix's origin remains unknown. While they are obviously alien in origin it is never stated who originally built them or for what purpose.