Hildur Ingveldardóttir Guðnadóttir (born 4 September 1982) is an Icelandic musician and composer. A classically trained cellist, she has played and recorded with the bands Pan Sonic, Throbbing Gristle, Múm, and Stórsveit Nix Noltes, and has toured with Animal Collective and Sunn O))). She has received various accolades, including an Academy Award, two Grammy Awards, and a Primetime Emmy Award.

Hildur has gained international recognition for her film and television scores, including for Journey's End (2017), Mary Magdalene (2018), Sicario: Day of the Soldado (2018), Todd Field's Tár and Sarah Polley's Women Talking (both 2022). For her score to Todd Phillips' psychological drama film Joker (2019), she won the Academy Award for Best Original Score, the BAFTA Award for Best Original Music, and the Golden Globe Award for Best Original Score, making her the first solo female composer to win in all three. She is also known for her work on the HBO miniseries Chernobyl (2019), which won her a Primetime Emmy Award, a BAFTA TV Award and a Grammy Award.