This is the one.... scared the H*LL out of me.
Superman
Season 1, Episode 25: The Unknown People: Part I
Original Air Date23 November 1951
Clark Kent and Lois Lane travel to Silsby, Texas, site of the deepest well ever drilled. But when they arrive, the well is being shut down and the oil company manager present isn’t saying why. Meanwhile, two short beings with large heads and furry hands come up from the well to explore. Luke Benson leads a mob of townspeople wanting to kill the “unknown people.” Despite Superman’s efforts to calm things down, the mob has tracked the two creatures to the top of a dam, trying to kill them. What the mob doesn’t know is the creatures cause things they touch to glow in the dark — and may be radioactive.
Season 1, Episode 26: The Unknown People: Part II
Original Air Date23 November 1951
One of the “unknown people” is shot while atop a dam near Silsby, Texas. Superman catches him before he falls into water and takes him to the Silsby hospital. Superman, in his Clark Kent identity, assists a doctor who operates on the creature. The doctor discovers his patient has all the organs and internal body structure as humans. Meanwhile, the Luke Benson-led mob tries to kill the other visitor from the center of the Earth. That creature escapes, later bringing up more of his people along with a weapon. Superman races to defuse an explosive situation.