Betan

Betans were the humanoid inhabitants of the planet Beta III.

Prior to 3800 BCE, the Betans were involved in a large-scale global war which threatened to destroy them as a race. In order to bring peace to his people, a Betan philosopher named Landru built a sophisticated computer -- also named Landru -- which "absorbed" members of Betan society, allowing their actions and emotions to be controlled by the computer. Once Landru's influence had spread over the planet, war, disease, crime, fear, and conflict had been eliminated. Landru led this new society -- now referred to as "the Body" -- through a group called Elders, and enforced its rules through Lawgivers. The tranquility of Betan society was interrupted only by the "Festival", a regular twelve-hour period of destruction and debauchery which began at the "Red Hour".

In 2167, Beta III was visited by the Federation starship, USS Archon (NCC-189), conducting a survey mission. The Archon was brought down by Landru, and its crew all either killed, or absorbed or killed by Landru.

A century later, the USS Enterprise (NCC-1701) was dispatched to Beta III to ascertain the fate of the Archon. The Enterprise crew were likewise confronted by Landru and threatened with absorption. But Captain James T. Kirk was able to deactivate the Landru computer by convincing it that it had destroyed the very society it was supposed to protect, thereby creating a paradox in its programming. 

With Landru's influence negated, Captain Kirk left Ensign Christopher Lindstrom and a team of sociologists behind to help guide the Betans in their new freedom. Additionally, the Corps of Engineers sent the USS Lovell to help bring Beta III's necessary automated systems back on line; Enterprise chief engineer Montgomery Scott also remained on Beta III to assist them. (, Book Two)

Mirror Universe
In the "Mirror Universe", the Andorian Imperial Guard conquered Beta III in 2155 on behalf of the Terran Empire. General Thy'lek Shran described the Betans as "little more than sheep." 


 * It is unclear what role, if any, Landru played in the history of this mirror Beta III.