Marion Cotillard is one of only six actors to have won an Academy Award for a role spoken mainly in a non-English language. Sophia Loren, Robert De Niro, Benicio Del Toro, Roberto Benigni and Christoph Waltz are the other five.
Marion Cotillard shrank her body from its petite 5'6" frame to Piaf's minuscule 4'11" stature by crippling and curling her form.
To help portray Édith Piaf, Marion Cotillard shaved back her hairline and shaved off her eyebrows, which were later penciled in, to better resemble the singer. She was also fitted with special dentures that better resembled Piaf's.
Director Olivier Dahan wrote the script with Marion Cotillard in mind as Édith Piaf before he had even met her, because he noticed a similarity between Piaf's and Cotillard's eyes.