Joseph Matthew Alwyn (born February 21, 1991) is an English actor. Alwyn made his feature film debut as the titular character in Ang Lee's 2016 war drama Billy Lynn's Long Halftime Walk and has since played roles in films such as The Favourite (2018), Boy Erased (2018), Mary Queen of Scots (2018), Harriet (2019), Catherine Called Birdy (2022), and The Brutalist (2024), as well as the BBC and Hulu drama series Conversations with Friends (2022).

Born in Kent and raised in North London, Alwyn developed an interest in acting during his teenage years. He acted in student productions at Edinburgh Festival Fringe, and obtained BA degrees in English literature and drama, and acting, from the University of Bristol (2012), and the Royal Central School of Speech and Drama (2015), respectively.

Alwyn worked with American singer-songwriter Taylor Swift on ten of her songs released from 2020 to 2022, including "Exile" and "Betty" from Swift's eighth studio album, Folklore, which won the Album of the Year at the 63rd Annual Grammy Awards. He won a Trophée Chopard at the 2018 Cannes Film Festival and appeared on the 2022 Time 100 Next list of rising stars.