Quentin Persifor Smith was an American philosopher. He was professor emeritus of philosophy at Western Michigan University in Kalamazoo, Michigan. He worked in the philosophy of time, philosophy of language, philosophy of physics and philosophy of religion.

He worked on the philosophy of time, philosophy of religion, naturalism and atheism, philosophy of Big Bang cosmology, and quantum cosmology.

Smith earned his Ph.D from Boston College. He has published over 140 articles and of his published books, he has authored three, co-authored two, and co-authored and edited seven. Smith is a philosophy editor for Prometheus Books and was the chief editor for Philo: A Journal of Philosophy. He has received honors from many academic institutions, including Phi Betta Kappa, the American Council of Learned Societies, the National Endowment for Humanities and the Rockefeller Award for the best philosophical work by an academically unaffiliated philosopher, for the article “The Infinite Regress of Temporal Attributions”.