Theodore John Stevenson is an English actor, best known for portraying the lead role of Horrid Henry in Horrid Henry: The Movie (2011). He went on to appear as Craig in the sitcom Millie Inbetween (2014–2018) and it's spin-off Flatmates (2019–2021), as well as playing Toby in the sci-fi drama Humans (2015–2018).

In 2007, Stevenson became an actor and took his first film role in Fred Claus as Young Nicolaus. He then appeared in the black comedy In Bruges in 2008. In 2010, he starred in Reuniting the Rubins where he played the role of Jake Rubins. In 2011, he took on his best-known role as Horrid Henry in Horrid Henry: The Movie^[1] where he worked alongside Tyger Drew-Honey and Anjelica Huston. He also appeared in the film's music video and appeared on Daybreak in late 2011.^[2]

A year after Horrid Henry: The Movie, Vertigo Films announced that Stevenson would star in an upcoming secondary school version of Streetdance called Streetdance Juniors which was renamed All Stars in June 2012, releasing on 3 May 2013. He stars alongside Akai Osei, Ashley Jensen, Kimberley Walsh and John Barrowman amongst others.^[3]

From 2014 to 2018, Stevenson had a main role in Millie Inbetween, a CBBC comedy-drama, playing the role of the main character Millie's stepbrother. He later reprised the role for the spin-off Flatmates.^[4]

Between 2015 and 2018, Stevenson had a main role as Toby Hawkins in the drama Humans where he has a crush on his family's synth, Anita.^[5]