The Tnuctipun are a fictional alien species in Larry Niven's Known Space series.

Two billion years before humans evolved, the galaxy was ruled by the Thrintun, who telepathically enslaved other species, including the Tnuctipun.

The Tnuctipun were extremely intelligent and invented most of the technologies from that era, including Stage Trees, Sunflowers, and stasis fields. In order to think creatively, the Thrintun allowed the Tnuctipun some freedom. The Tnuctipun used that freedom to stage a rebellion against their masters, the culmination of a carefully thought out plan.

The true nature of some of their inventions became clear: Bandersnatchi, thought to be non-sentient livestock, were in fact intelligent, created as spies immune to telepathy. Sunflowers turned against their masters and burnt Thrint homes to the ground.

The war escalated until the Thrintun, rather than accept defeat, employed a device that amplified the sphere of influence of a Thrint's mind control to encompass the entire galaxy. And they gave a simple command: die. And everything in the galaxy that had evolved a backbone perished. The Thrint civilization, without slaves, collapsed.

The Thrintun are then believed to have evolved into the Grog, intelligent telepathic aliens who, incapable of locomotion, are dependant on their prey to survive.