Princess O'Rourke is a 1943 American romantic comedy film directed and written by Norman Krasna (in Krasna's directorial debut), and starring Olivia de Havilland, Robert Cummings and Charles Coburn. Krasna won the 1944 Oscar for Best Original Screenplay.

Although conceived as a vehicle for de Havilland, Princess O'Rourke turned out to be a troubled project that led to the de Havilland Law, that changed the status of contracts in the U.S. film industry. Filmed in 1942, the release was held up for one year due to legal issues that resulted from the production.

During World War II, Princess Maria and her uncle Holman, exiles from their (unnamed) conquered European country, live in New York City. Holman hopes that his niece will marry and produce a male heir as soon as possible, but she is not interested in his preferred choice, Count Peter de Chandome, or the other candidates that he has suggested.

While flying to California incognito as "Mary Williams", the princess—fearful of flying—is accidentally given too many sleeping pills. When the Douglas DST airliner returns to New York because of bad weather, the crew cannot wake her. The pilot, Eddie O'Rourke, takes care of her, still unaware who she is. She wakes up the next morning in his apartment wearing his pajamas.

To explain her absence, Maria tells her uncle that she slept at the airport. She spends the day with Eddie, his friend and co-pilot, Dave Campbell, and Dave's wife Jean (who had put Maria to bed). "Mary" tells them she is a war refugee and was traveling to California to work as an upstairs maid. She and Eddie quickly fall in love. With both Eddie and Dave about to join the United States Army Air Forces, Eddie impulsively proposes to Mary. She accepts, but sadly believes that, as a princess, she cannot marry him.

A Secret Service agent assigned to protect Maria tells her uncle of the relationship. Holman is not opposed to Maria marrying a commoner, and is pleased to learn that Eddie is one of nine brothers and his father one of 11. Holman also knows that his niece marrying an American would strengthen his country's vital relationship with the United States. To Maria's surprise and joy, he permits the marriage, and Eddie is stunned to learn that his poor European refugee is actually royalty.

President Franklin D. Roosevelt invites Maria and Eddie to stay at the White House. Given a crash course in royal protocol by a representative of the State Department, Eddie becomes increasingly uncomfortable with the conditions attached to the role of prince consort and being financially supported by his wife, with no career other than fathering an heir. While discussing the prenuptial agreement, he finally rebels when he is informed he must surrender his American citizenship. After making an impassioned speech about how lucky he is to be an American, Eddie asks "Mary" to choose between him and her family. Maria obeys her uncle and leaves the room; a disappointed Eddie calls her a "slave". Holman locks her in the Lincoln Bedroom.

After much crying, Maria writes a note and slips it under the door for Roosevelt's dog, Fala, to deliver to his master. In the middle of the night, the President summons a Supreme Court judge to marry Eddie and Maria. Afterward, the newlyweds sneak out of the White House. On the way out, Eddie bumps into a man standing behind the door; he mistakes the man for a guard. Outside, Maria tells him that the "guard" was actually the President. Astonished, Eddie exclaims, “I tipped him a buck! And he took it!”