Tosk

The Tosk are a race of sapient creatures native to the Gamma Quadrant in the Milky Way Galaxy.

Biology
The Tosk resemble reptilian humanoids. They were created to be the perfect prey by a hunter race. The Tosk possess the ability to become invisible to the naked eye. They also have great agility and require 17 minutes of rest per rotation. Tosk also keep liquid nutrients stored throughout their bodies for greater efficiency.

Culture
The Tosk or 'The Hunted' were created to be hunted as sport by a sapient race. Sapience for their kind was only included so that the hunt would be more challenging. They were conditioned by their alien creators in such a way that it is an honor for them to be hunted and killed. The Hunters that created them in turn respect and admire their creations, who accomplish this, even though sometimes Hunters are killed by their prey. The only disgrace for their kind is to be easily captured, or seek protection from another race. In fact Tosk are forbidden from speaking of their place in the Hunters' society, quite possibly to prevent other races from learning of the amoral hunts. The Tosk who break this rule suffer and are forced to return to the homeworld, to be ridiculed and caged like an animal.

Source

 * Deep Space 9: "Captive Pursuit"