The Locrix are described by Val Yor as "vicious killing machines" whose goals are to achieve total galactical domination.
Their first and only appearance was in the episode "Troq", where the galactic hero Val Yor arrives on Earth to fight of a group of invading Locrix. Val Yor recruits the Teen Titans and has them (except Starfire, becuase he has a prejudice against Tamaranean) attack the Locrix. They are all eradicated at the end of the episode with the combined forces of the Titans and Val Yor.