- Has an identical twin brother, actor Luke Treadaway.
- Formed a punk band called Lizardsun with his twin brother, in secondary school.
- He and Luke were the first set of twins to be accepted into the National Youth Theatre, at age 16.
- Spent months strapped to Luke as a conjoined twin fronting a punk band in the 2006 film Brothers Of The Head, his first professional acting job.
- Is a credited songwriter, with two songs appearing on the 2006 Brothers Of The Head soundtrack.
- Made his theater debut in Mark Ravenhill's Over There at the Royal Court in 2009.
- Attended a six-week cowboy boot camp in New Mexico for his role in the 2013 action flick The Lone Ranger.
- Sam Treadaway — Brother
- Luke Treadaway — Brother
- London Academy of Music and Dramatic Art, London, England (2006)