John DiLeo is one of today's foremost historians and commentators on classic American film. For more than three decades, he has championed the artistry of Hollywood through his books, lectures, interviews, and film programming, earning a reputation for uncovering overlooked performances, rediscovering forgotten classics, and illuminating the enduring appeal of the movies. He is the author of numerous acclaimed books on film, including And You Thought You Knew Classic Movies, praised by legendary critic Pauline Kael as "the smartest movie quiz book I've ever seen"; 100 Great Film Performances You Should Remember—But Probably Don't; Screen Savers; Tennessee Williams and Company; Screen Savers II; Ten Movies at a Time; and There Are No Small Parts, his celebration of unforgettable supporting performances. His work has been praised by figures including Robert Osborne, Adolph Green, and the Washington Post, while Turner Classic Movies has featured films from his books in dedicated programming.

A graduate of Ithaca College with a B.F.A., DiLeo was born in Brooklyn and raised on Long Island. He continues to write, lecture, and share his lifelong passion for the movies through his books and public appearances.