O'Fallon may refer to:
People Caroline Schutz O'Fallon (1804-1898), American benefactor and philanthropist James O'Fallon (bef 1756–1786), Irish Roman Catholic clergyman John O'Fallon (1786–1865), American businessman, philanthropist, and military officer Peter O'Fallon, American television director
Places O'Fallon, Illinois, United States O'Fallon Township, St. Clair County, Illinois, United States O'Fallon, Missouri, United States O'Fallon Park O'Fallon, St. Louis, a neighborhood in the city of St. Louis, Missouri, United States O'Fallon Street (St. Louis)
See also O'Fallons, Nebraska, United States Fallon (disambiguation)