Nebula

"You're the one who wanted to win, but I just wanted a sister. You were all I had, but you just needed to win. Thanos pulled my eye from my head. He tore my brain from my skull, and my arm from my body... because of you."

Nebula is one of the main characters in MCU's Guardians of the Galaxy.

Pre-Guardians of the Galaxy
Nebula was born in Luphom, the homeworld to the Luphomoids. However, her parents were killed and she was kidnapped by Thanos. Throughout her childhood, she was tortured by Gamora and their other siblings.