The 1918 Northwestern Purple team was an American football team that represented Northwestern University during the 1918 Big Ten Conference football season. In their fifth and final year under head coach Fred J. Murphy, the Purple compiled a 2–2–1 record (1–1 against Big Ten Conference opponents) and finished in sixth place in the Big Ten Conference. Northwestern's quarterback Marshall Underhill was selected as a first-team player on the 1918 Big Ten Conference football season.