Mario Casas Sierra is a Spanish film and television actor. He is known for his roles in the films "Summer Rain", "Three Meters Above the Sky", as well as in the series "Los hombres de Paco", "El Barco" and others.

His film debut was in Antonio Banderas's film "Summer Rain". In the same year, M. Casas began filming the television series SMS. Throughout 2009, the actor appeared in several films: "Brain Drain", "Sex, Parties and Lies". On December 3, 2010, the film "Three Meters Above the Sky" was released, in which Casas played the lead male role. For this role he received the ACE Award as best new actor and was nominated for the Fotogramas de Plata award.

In 2012, the sequel to this story was released — "Three Meters Above the Sky. I Want You" (Tengo ganas de ti) — under the direction of the same director Fernando González Molina, with Clara Lago joining the cast. In 2011, he was invited to play the role of Ulises in the series "El Barco".