Isobel Dorothy "Bel" Powley (born 7 March 1992) is an English actress best known for playing Daisy Miller in the CBBC television series M.I. High. Powley plays the protagonist in the 2015 film The Diary of a Teenage Girl, which premiered at the 2015 Sundance Film Festival. From 2007 until 2008 Powley was one of the lead characters in M.I.High, starring in 23 episodes alongside Rachel Petladwala and Moustafa Chousein-Oglou. In addition to M.I.High, Bel Powley has also appeared in several other productions such as Murderland (3 episodes, 2009), Little Dorrit (2008), The Bill (2008) and The Whistleblowers (2007).
Powley was born in the Hammersmith district of London, England, to British actor Mark Powley and casting director Janis Jaffa. Her mother is Jewish. In 2015, Powley portrayed Princess Margaret in the biographical comedy-drama A Royal Night Out alongside Emily Watson and Rupert Everett and played the lead role of Minnie Goetze in the comedy-drama The Diary of a Teenage Girl, alongside Kristen Wiig and Alexander Skarsgård, for which she received rave reviews.