Leisa Gwenllian is a Welsh actress. She starred in the Welsh-language film Effi o Blaenau (2026). She was named a 2026 Screen International Star of Tomorrow.
Early life and education Gwenllian was born and brought up in North Wales. Her mother is Beca Brown, a Plaid Cymru member of the Senedd. She credits eisteddfods with giving her opportunities to gain confidence at performing in public through competitions in recitation, monologues and choral singing. She studied at Canolfan Gerdd William Mathias in North Wales and later trained at the Oxford School of Drama, graduating in 2024. Her audition piece for the drama school was a monologue from Iphigenia in Splott.
Career Gwenllian had an early role in Rocket's Island, appearing as Bethany Summer from 2014 to 2015. She went on to appear in Welsh soap opera Rownd a Rownd, S4C drama Itopia, the film On the Sea (2025), and the second series of Wales-set mystery-drama series The Light in the Hall: Still Waters/Y Golau:Dŵr (2025), and as Kath Bevan in Sky Atlantic crime drama Under Salt Marsh alongside Kelly Reilly and Rafe Spall (2026). She has been a voice actor in several animation productions from Sain and other companies.
Gwenllian made her first film appearance with the part of Lois in the film On the Sea (2025), followed by the maid Clara in Madfabulous (2026). However, her first leading role was in Effi o Blaenau (2026). She received praise for her performance as Effi in this Welsh-language film adaptation directed by Marc Evans from Gary Owen's one-woman play Iphigenia in Splott. Her portrayal of Effi was described as "remarkable", portraying a young woman shaped by poverty and neglect in the dramatic post-industrial landscape of Blaenau Ffestiniog and North Wales.
Filmography Film Year Title Role Notes2025On the SeaLoisMadfabulousClara2026Effi o BlaenauEffi
Television Year Title Role Notes2014–2015Rocket's IslandBethany SummerRecurring role, 19 episodes2021Rownd a RowndKylie WalshSeries regular2022–2024ItopiaLwsi HunterSeries lead2025The Light in the HallYoung Eve 2025Under Salt MarshKath Bevan
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