Rance was a Betarian male engineer that lived in the Corvan II mining colony. When the colony was attacked by Klingons, he broadcast a call for help. (DIS: "The Butcher's Knife Cares Not for the Lamb's Cry")
Rance was portrayed by actor Dennis Andres.
His name and occupation was taken from the episode's end credits. According to StarTrek.com, his first name was Sterling.