On top of being strong, the female leads in Stephen King's novels are shown as overcomers, frequently triumphing over whatever was tormenting them. Donna Trenton in Cujo kills the terrifying dog, ending the torment and finding revenge for the death of her son. She is triumphant, powerful. A woman killing a beast is not very common in many horror scenarios, so this is a powerful and rather feminist moment. Carrie White triumphs over everyone who tormented her in Carrie. She finds her revenge on the terrible kids at her school and her abusive, crazy mother. In 11/22/63, Sadie Dunhill perished but emerged victorious in the sense that she makes a difference in the world no matter what timeline she is in. She escapes an abusive relationship and supports her new one with all that she is. She's a survivor. It's a relief to see stories in which females are not just victims. Women are shown as powerful, determined, and intelligent.
Although these women triumph over evil, there is often not a valid reason why they are in these situations in the first place. The circumstances are unnecessary and could be told without putting women in these terrible situations.
[P1] Stephen King writes women as powerful overcomers. [P2] This is rare for many horror novels.
Rejecting the premises
[Rejecting P1] The situations they are placed in to overcome are sexist.