"Once Upon a Dream" is a song written in 1959 for the animated musical fantasy film Sleeping Beauty produced by Walt Disney. It is based on Tchaikovsky's ballet of the same name, more specifically the piece "Grande valse villageoise" ("The Garland Waltz"). It is the theme of Princess Aurora and Prince Philip and was performed by a chorus as an overture and third-reprise finale.

Lana Del Rey covered it for the 2014 dark fantasy film Maleficent. The cover received generally positive reception. Forbes called the cover "moody and low-key" while Stereogum described it as "swoony" and "spaced-out". Hypable said the cover was "much darker" than the original and pointed out the "slight radio effect" over Del Rey's and called her performance of the song "haunting". Spin said of the song snippet from the trailer "Smoky vocals, a bewitching come-hither delivery, and delicate piano turn the 1959 fairytale song into a haunting lullaby." Complex remarked that Del Rey's cover had a "somber and sinister" feel in comparison to the original.