The final season of Stranger Things brought back Linnea Berthelsen as Kali - but who else needs a refresher of the infamous season 2 episode that originally introduced Eleven's "sister"? During part 1, which premiered on Wednesday, November 26, Hopper (David Harbour) and Eleven (Millie Bobby Brown) prepared for one final battle with Vecna (Jamie Campbell Bower). They got their shot once they were both in the Upside Down but eventually they got caught by newcomer Dr. Kay (Linda Hamilton). Initially Hopper planned a mission that would kill him but keep Eleven safe.