Bela Okmyx was boss of the Northside Territory, the largest on Sigma Iotia II, a planet whose society was based on Earth's Chicago gangster period. A book (referred to as "The Book") entitled "Chicago Mobs of the Twenties" was left by the Horizon, a 22nd century Federation ship, and the entire Iotian culture has been formed by this one book.
In 2268, James T. Kirk visited the planet to update its progress. Okmyx offered to cut Kirk in on the action, if Kirk helped him take over the planet by providing him with "heaters". When Kirk refused the request, he and Spock were taken hostage and Okmyx threatens to kill them. Kirk was able to escape.
Kirk was able to intervene and end the turf war between the bosses, when he has the ship fire phasers on stun in the surrounding area to demonstrate the power of the "Feds". The Mobsters are convinced and agree to Federation control with Okmyx the planetary leader and Jojo Krako, his rival as his Lieutenant. (TOS: "A Piece of the Action")
Bela was played by actor Anthony Caruso. His surname has appeared in many subsequent texts, including the Star Trek Concordance, The Star Trek Compendium, the Star Trek Encyclopedia and StarTrek.com as the way it was pronounced throughout the episode: "Oxmyx". The correct spelling, as seen on posters throughout the episode, was in fact "Okmyx".
The "Okmyx" spelling is also found in the 'Final Draft' of the shooting script, dated 30 October 1967 – with revised pages dated 31 October 1967. Although pronunciation is provided for other characters in this episode, no such guidance is provided for "Okmyx." The end credits simply credit the character as "Bela."
The character appeared again in an issue of DC Comics's second volume comics series, "... Let's Kill All the Lawyers!", where he revealed at Kirk's trial that the captain's cut of Iotia's "action" was still being skimmed for him.