Laura Benanti As Kara's Mom In "Supergirl", Replaced By Erica Durance
Since Laura was from New York City, she couldn't continue portraying Alura Zor-El, since the second season saw production in Vancouver. Erica Durance, who portrayed Lois in Smallville, was given the part of Kara's mother, hiring another actress who had already portrayed Lois Lane in another show.
Also, how would anyone be able to tell when some background character in GoT was replaced? There were a ton of them, and they all looked the same.