Hildur Ingveldardóttir Guðnadóttir (born 4 September 1982) is a classically trained Icelandic cellist who has played and recorded with the bands Pan Sonic, Throbbing Gristle and Múm, as well as her solo project Lost in Hildurness. She has also toured with Animal Collective and Sunn O))). She collaborated with Jóhann Jóhannsson on the score to Garth Davis' Mary Magdalene. In 2018, she created the score for director Stefano Sollima's film Sicario: Day of the Soldado. 　　In 2007, she released a solo album, Mount A, on which she attempted to "involve other people as little as I could." It was recorded in New York City and Hólar in the north of Iceland. 2009 saw the release of her second solo album, Without Sinking on the UK-based audio-visual label, Touch. 　　As well as the cello, Hildur also sings and arranges choral music, once arranging a choir for performances by Throbbing Gristle in Austria and London. As a composer she has written a score for the play Sumardagur ("Summer Day") performed at Iceland's National Theatre. She has also written the score for the Danish film Kapringen (A Hijacking). 　　She is set to score the upcoming Joker film starring Joaquin Phoenix, directed by Todd Phillips.