Pataky was born as Elsa Lafuente Medianu in Madrid, Spain, the daughter of Cristina Pataky, a publicist, and Jose Francisco, a chemist. She has Romanian and Hungarian ancestry, and is fluent in Spanish, French, English and Romanian. Pataky attended the Universidad de San Pablo and studied journalism.

During this time, Pataky also enrolled in acting classes. She was also a member of the Madrid theatre company, Teatro Cámara de Ángel Guitiérrez. Eventually, she left school when she was cast in the television series Al salir de clase.

With the success of Al Salir de Clase, Pataky received her first film offer, El arte de morir. Some of her subsequent films were co-productions with the UK and France, which introduced her to working in English and French.

Pataky has appeared in over ten Spanish films and most recently crossed over into the French market with her co-starring role in the 2004 box office hit, Iznogoud. She also appeared in a supporting role in the David Ellis-directed film Snakes on a Plane (2006), alongside Samuel L. Jackson. She is currently receiving good reviews for her work in the Spanish film Ninette, helmed by Oscar winner José Luis Garci.