- Gender: Female
- Birthday: 2000-07-01 ( 23 years old )
- Place of Birth: Wellington, New Zealand
- Also Known As: Thomasin McKenzie-Harcourt / Tom McKenzie / Thomasin Harcourt McKenzie / Τόμασιν Μακένζι / 토마신 맥켄지 / Томасин Маккензи
Thomasin Harcourt McKenzie (born 26 July 2000) is an actress from New Zealand. After a minor role in The Hobbit: The Battle of Five Armies, she rose to critical prominece with the lead role in Debra Granik’s 2018 drama film Leave No Trace. After supporting roles in the 2019 films The King, Jojo Rabbit and True History of the Kelly Gang, as well as the 2021 thriller Old, Edgar Wright’s psychological horror film Last Night in Soho established her as one of the industry’s lead actresses.