Monsters, Inc.

Due to her limited vocabulary, Mike and Sulley only know the little human girl as "Boo." But a small detail suggests that she has another name. One of Boo's drawings is signed "Mary" repeatedly. The little girl who provided Boo's toddler babbling is named Mary Gibbs. One of the novelizations of the film confirms that this is also Boo's real name.

ABOUT MARY GIBBS: The production team had a hard time getting her to sit still to say her lines, so the followed her around the studio with a microphone and pieced Boo's dialogue together from the thing Gibbs said while playing