Frost is one of the eleven new characters that debut in Mortal Kombat: Deadly Alliance. She served as Sub-Zero's apprentice for the Lin Kuei. Sub Zero had to banish Frost from the Lin Kuei due to arrogance and hostility to anyone in his clan. In Mortal Kombat 11, she was heavily cyberised by Kronika and she would assist the Cyber Lin Kuei to dominate and she would try to become the new leader of the Lin Kuei replacing Sub-Zero.
Between these two, it's pretty obvious who I'm going with. Kelly Hu as Frost wasn't used that much in Mortal Kombat X while the developers started to use Sara Cravens as Frost more often in Mortal Kombat 11.