Actually, one of Mariah Carey's No. 1 singles was intended to be the title song for a film starring Dustin Hoffman. I'll let you think about which one it might be while I answer the first part of your question. There's no one person who automatically selects who will sing a movie's theme song, but it's usually one of several people: the music supervisor, the director, the producer, or a label executive who is involved with the soundtrack--or some combination of those people. Now, let's talk about the film song Mariah wrote and recorded--even though it wasn't heard in the movie. The soundtrack to the film "Hero" was a project of Epic Records. Label executives wanted Mariah Carey to sing the film's theme, but she was so hot, they assumed she wouldn't agree to be the vocalist. So instead, they asked her and producer Walter Afanasieff to write something for the movie. Afanasieff attended a screening and was told that Gloria Estefan was the likely candidate to record a title song. At the same time, Carey and Afanasieff were working on Mariah's "Music Box" album. Afanasieff tells what happened next: "We were in the studio and came to a break. I told Mariah about this movie. Within two hours, we had this incredible seed for this song, 'Hero.' It was never meant for Mariah to sing. In her mind, we were writing a song for Gloria Estefan ... and we went into an area that Mariah didn't really go into. In her words, it was a little bit too schmaltzy ... or too old-fashioned." Mariah and Walter had almost finished the song when Tommy Mottola, President/COO of Sony Music and at the time Carey's fiancee, walked into the studio. He heard the song and they told him it was for a movie. Afanasieff recalls Mottola responding, "Are you kidding me? You can't give this song to this movie. This is too good. Mariah, you have to take this song." The lyrics were completed after the decision was made to keep the song for Mariah. Afanasieff told the people working on the soundtrack he didn't have anything for them, and Estefan never knew that Carey's "Hero" was originally intended for her. The song that ended up in the film was "Heart Of A Hero," written, produced, and recorded by Luther Vandross. So aside from her remake of "Endless Love" (recorded with Luther Vandross), Carey has not charted with a movie song, but that could still happen in the future.