Triskelion

Triskelion is a planet located in a trinary star system.

Triskelion is ruled by a group of three powerful disembodied brains called the "Providers."

The Providers' society revolved around betting their monetary reserves on various aspects of captured slaves' lives, including open combat with one another.

The Federation starship USS Enterprise, NCC-1701 was obligated to visit the planet, in order to secure the release of several crew kidnapped by the Providers. Upon arrival, the Enterprise discovered numerous species were enslaved on the surface, including their missing crew. Eventually, to free the slaves, Kirk entered into open combat, betting not for money, but on 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.

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