Named for their three eyes. They also have three fingers on each hand and a triangular mouth. They are 5-foot-tall (1.5 m) bipedal humanoids, with long legs, short torsos, and improbably flexible neck vertebrae. Their "neckless" neck is hidden under rolls of chrome yellow skin. They can snap their head around instantly to look directly backwards with their three deep-socketed eyes. Their mouth is triangular, with the edges of yellow, serrated bone knives showing behind three gristle lips. They have a complex elbow and a three-clawed hand. The atmosphere of Earth-like worlds is poisonous to them.
Other races regard Trinocs as paranoid. The Trinoc regards Humans as "insufficiently suspicious". Puppeteers trade with Trinocs, largely through robots.