Harry Gilby (born 21 August 2001) is an English actor, best known for playing a young J. R. R. Tolkien in the film Tolkien (2019) and Æthelstan in the fifth season of The Last Kingdom (2022) and the follow-up film The Last Kingdom: Seven Kings Must Die (2023).

He attended Sutton Bonington primary school before joining Trent College when he was 11.

[1] Gilby played Nathan in the original cast of The Full Monty at the Noël Coward Theatre in London's West End.

[2] Gilby made his acting debut in 2016, when he played a village lad in an episode of Jericho.

He has also appeared in three episodes of Casualty as Toby Williams, a young boy dying of leukemia.