Cave made her acting debut in the drama
Summerhill, shown on
CBBC in early 2008. She won the role of
Lavender Brown in the film
Harry Potter and the Half-Blood Prince through an open casting call held on 1 July 2007. Cave, who came from an agency, beat over 7,000 girls who turned up for the audition. She also performed the voice of Lavender in the video-game adaptations of
Harry Potter and the Half-Blood Prince and
Harry Potter and the Deathly Hallows: Part 2. In June 2009, she made her West End début, playing Thomasina in a revival of
Tom Stoppard's Arcadia at the
Duke of York's Theatre. That December, Cave had a minor role in the 2009 film
Inkheart as a water nymph. She appeared in the play
Breed at
Theatre503, playing the role of Liv, from 21 September to 16 October 2010. She won the Off West-End stage award for People's Choice for Female Performance. On 4 February 2011, she appeared as a one-off character, Hermione, on the CBBC children's drama
Sadie J. Cave runs the website Pindippy, and its associated YouTube channel of the same name, which features short videos written by and starring Cave herself, with occasional appearances from some of her
Harry Potter costars, including her close friend,
Evanna Lynch. She played the title character in a 2012 production of
J. M. Barrie's
Mary Rose at the DogOrange Theatre, in London. That same year, she appeared as Zazzy in the final episode of season 2 of ''
Grandma's House'', which aired on 24 May 2012, and in the role of elder Biddy in 2012's
Great Expectations, based on
the novel by
Charles Dickens and directed by
Mike Newell. During the filming of
Great Expectations, Cave worked alongside her younger sister Bebe (who played the younger Biddy) and was also reunited with her
Harry Potter costars
Helena Bonham Carter,
Robbie Coltrane, and
Ralph Fiennes. By June 2012, Cave had amassed over 30,000 followers on her Twitter account. Her 2018 Edinburgh Fringe show
Sunrise was described as an "emotionally intelligent [and] honest" performance. and has since been published as a playtext by Nick Hern Books. ==Other activities==