Page, 83, died of pneumonia and stroke complications at Cedar-Mount Sinai Hospital on Friday, her son, Gregory Orr, told the Los Angeles Times.
While Page had a 20-year career in movies and television, her best-known role was probably the first. She was only 17 when she read for the part of Annina Brandel, the young refugee so desperate for visas for herself and her husband that she considers agreeing to a proposition from the French police officer played by Claude Rains.
Orr said that his mother found "Casablanca" "corny and old-fashioned" when her stepfather brought the script home but changed her mind about trying for a part at her acting coach's suggestion when she learned Ingrid Bergman had been cast in the lead.
Warner would not give her a contract with his studio. She appeared in a number of other movies, including "Kismet," where she played Ronald Colman's daughter.
Page retired in 1962. Her marriage to William T. Orr, an actor who became a Warner Bros. executive, ended in divorce.