Harry John Newman Treadaway (born 10 September 1984) is a British actor. His credits include Control (2007), Fish Tank (2009), Pelican Blood (2010), Flight of the Storks (2012), Mr. Mercedes (2017-2018), The Crown (2019), Star Trek: Picard (2020), Deceit (2021), and The Chemistry of Death (2023).

Early life and education
Born at the Royal Devon and Exeter Hospital in Exeter, Devon, Treadaway was brought up in Sandford, Devon. His father is an architect and his mother is a primary school teacher. He has two brothers, older brother Sam (an artist) and twin Luke. Treadaway and Luke attended Queen Elizabeth's Community College in Crediton, Devon, where they played in the twice Devon Cup winning Rugby Union team.

Inspired by a love of Eddie Vedder and with support from their secondary school drama teacher, the twins formed a band called Lizardsun. They also both joined the National Youth Theatre.

Treadaway studied acting at LAMDA and graduated in 2006.