Antrons are four-armed creatures from Microspace, apparently good at being assassins. One of them served as part of the Ministry of War under Membros during their invasion of Earth.
An Antron infiltrated the headquarters of the Ministry of Defense to try and kill Baron Karza, killing the base's Acroyear II guards on the way in. The Antron attacked Karza, but the Baron used his mastery of Enerchange to launch his hand at the attacker and knock him back. The Antron tried to get up, accusing Karza of being a "murderous traitor", but Karza refused to die, wounding the assassin by launching his fingers as missiles before killing it with lasers from his eyes. Micronauts #3
An Antron, referred to simply as "Antron", was part of the crew of Membros's ship Wrath of Karza #2 that attacked Skywarp in Scotland in order to neutralise G.I. Joe. Wrath of Karza #1 When the ship shot down the Heliopolis, Antron was responsible for manning the guns, which Raith congratulated him on. Antron left the ship along with its teammates to capture the Micronauts; during the fight with Acroyear, it tried to attack the super-soldier but had one of its arms sliced off, before the Acroyear was taken down by Membros. Wrath of Karza #2
- It's not clear whether the Antron seen in Wrath of Karza is the same as the one seen in Micronauts #3, or a different member of the same species. (Or, indeed, a different species based on the same toy; the two do look very different, though that could be down to a different artist.)
- Antron's original Micronauts toyline packaging described it as "the six-limbed invader from the faraway galaxy of Thoraxid", but it's unknown if it comes from there in IDW continuity.
- Antron on Inner Space Online