is an Irish singer and actress. She began her career in theatre and rose to prominence when she starred as Matilda Wormwood in the film Matilda: The Musical (2022). 
When the musical Once returned to Dublin's Olympia Theatre in 2017, Weir played Ivanka. She made her feature film debut in the 2018 thriller Don't Leave Home and her television debut as Laura in the 2019 crime drama Darklands. She appeared in Tony Finnegan's productions of Annie, The Wizard of Oz, and Oliver! at the National Concert Hall.

Weir was eleven when she was cast as the titular Matilda Wormwood in the film adaptation of Matilda the Musical for Netflix, and thirteen by the film's premiere in 2022.