David Halliday (March 3, 1916 – April 2, 2010) was an American theoretical physicist and renowned textbook author, best known for coauthoring Physics and Fundamentals of Physics with Robert Resnick (and later Jearl Walker). Widely translated and used in university-level physics curricula, these texts are celebrated for their clear diagrams, pedagogical style, and thought‑provoking problems. The American Physical Society honored Fundamentals of Physics as the most outstanding introductory physics text of the 20th century.