Midro is a Troglyte miner and member of the Disruptors in The Cloud Minders, a hot-headed follower of Vanna who distrusts Kirk's offer of filter masks.
Midro is a Troglyte of the planet Ardana in the Original Series episode The Cloud Minders. He works in the zenite mines on the surface and belongs to the Disruptors, the group led by Vanna that resists the rule of the cloud city Stratos.
When Kirk comes to the mines with filter masks meant to block the gas that dulls the miners' minds, Midro is one of the Disruptors who seize him. He is more interested in holding a starship captain hostage than in listening.
Vanna sends him away with orders while she decides what to do. Kirk then seals himself, Vanna and later Plasus in a chamber full of raw zenite to prove the gas is real, the demonstration that at last makes both sides take the masks seriously.