Triskelion

Triskelion was an inhabited planet located in the M24 Alpha star system. The planet was the homeworld of the Providers.

This world was ruled by a cabal of three powerful disembodied brains called the Providers. The Providers' society revolved around betting their monetary reserves (counted in a currency known as a quatloo) on various aspects of captured slaves' ("thralls") lives, including open combat with one another. The thralls lived in a compound on the lower hemisphere of the planet.

The Federation starship USS Enterprise (NCC-1701) under command of James T. Kirk was obligated to visit the planet to secure the release of several crew kidnapped by the Providers. Upon arrival, the Enterprise discovered numerous species enslaved on the surface as thralls, including their missing crew. Eventually, to free the thralls and his crewmates, Kirk entered into open combat against three drill thralls, betting not quatloos on his victory, but the condition of freedom for all if he was victorious, or enslavement of the Enterprise crew if he lost. He won, and the Enterprise left the system shortly afterward.

Another condition of the wager was that the Providers would educate the remaining thralls and allow the development of a free society on the planet. 

In 2328, Triskelion was the home for the Triskelion Orbital Station. 

In the 24th century the Cardassians traded with Triskelion during the Bajoran Occupation, as did the Bajorans after they took control of Deep Space 9.