In 1972, Blair was selected from a field of 600 applicants for her most notable role as Regan, the possessed daughter of a famous actress, in William Friedkin's The Exorcist (1973). The role earned her a Golden Globe and People's Choice Award for Best Supporting Actress as well as an Academy Award nomination for Best Supporting Actress. Film critic and historian Mark Clark notes that in her performance, "Blair matches [adult co-star] Ellen Burstyn note-for-note. " Despite the film's critical successes, Blair received media scrutiny for her role in the film, which was deemed by some as "blasphemous," and Blair has said the film had significant impact on her life and career. After the film's premiere in December 1973, some reporters speculated about Blair's mental state, suggesting the filming process had resulted in her having a mental breakdown, which Blair denied, and she would later receive anonymous death threats. To combat the rumors and media speculation surrounding her, Warner Bros. sent the then-14-year-old Blair on an international press tour in hopes of demonstrating that she was "just a normal teenager. "