Usually the role was held by a magistrate, one of the government officers of the Roman republic. At times lanistas, such as Batiatus or Vettius would play the role, though usually due to the lack of a magistrate being present.
Editors also existed for smaller fights, although the term editor would be used very lightly. Numerius, for his 15th birthday, has Spartacus and Varro demonstrate a fight in Batiatus' villa. Although originally intended to be an exhibition match, when asked to pass judgement on the fallen warrior, he extends his arm and shows his thumb down, meaning that Varro was to die.