Reactron is Benjamin Krullen, one of the oldest and greatest enemies of Supergirl. A psychopathic, lecherous, bullying, mass-murdering thug who holds an irrational grudge against Supergirl and, by extension, her family and her race, Reactron wears a protective suit of armor which gives him the ability to generate and project high levels of energy capable of killing a Kryptonian in just one blow. He has been known to gleefully consent to being turned into a guinea pig and human bomb for the chance to kill Supergirl and her whole race. Reactron was created by Paul Kupperberg and Carmine Infantino in 1983, first appearing in Supergirl (Volume 2) #8.

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