Isabella May Ramsey (born September 2003) is an English actor. They are known for their breakout role as young noblewoman Lyanna Mormont in the HBO fantasy television series Game of Thrones (2016–2019), and subsequent television roles as Mildred Hubble in the 2017 CBBC series The Worst Witch, the voice of the title character in the Netflix animated series Hilda (2018–present –  as of 2023), and Jane Grey in the 2022 Starz drama Becoming Elizabeth.

They starred in the 2022 historical comedy film Catherine Called Birdy and currently stars as Ellie in the 2023 HBO drama series The Last of Us.