Zabo is a hoodlum in the gang of Jojo Krako on Sigma Iotia II who snatches Kirk off the street at gunpoint in A Piece of the Action.
Zabo is an Iotian gangster in the Original Series episode A Piece of the Action. He is a lieutenant of Jojo Krako, boss of the South Side territory and chief rival of Bela Oxmyx, on a world that has modelled its whole society on a book about the Chicago mobs of the 1920s.
When Kirk slips away from Oxmyx's men, Zabo and a partner are waiting with machine-guns and take him to Krako, who wants the Federation's weapons for himself. Zabo stands guard while his boss makes the offer and threatens Kirk when he refuses.
Later Kirk and Spock, now dressed as mobsters, storm Krako's headquarters and Zabo is among the men they overpower. He ends up with the other hoods at Oxmyx's office when Kirk forces the bosses into a single syndicate.