Robert Jay Arthur Jr. (November 10, 1909 – May 2, 1969) was an American writer and editor, primarily known for his work in the mystery and supernatural genres. He is best remembered for creating the "The Three Investigators" series for young readers, featuring Jupiter Jones, Pete Crenshaw, and Bob Andrews. In addition to his books for younger audiences, Arthur wrote numerous short stories and radio plays and served as a scriptwriter for radio shows such as "The Mysterious Traveler" and "The Sealed Book." He collaborated with famous figures like Alfred Hitchcock, whose name was used to introduce "The Three Investigators" series in order to attract a wider audience. Despite passing away at a relatively young age of 59, Arthur's contribution to mystery and adventure literature, especially for young readers, remains influential.