Harron is probably best recalled for his roles in the three epic Griffith films: 1914's "Judith of Bethulia", opposite Blanche Sweet, Mae Marsh, Henry B. Walthall, and Dorothy and Lillian Gish; 1915's controversial all-star cast "The Birth of a Nation"; and 1916's colossal multi-scenario "Intolerance" opposite such popular stars of the era as Lillian Gish, Mae Marsh, Miriam Cooper, Wallace Reid, Harold Lockwood, and Mildred Harris. One of Harron's most popular roles of the era came in 1919 when he starred opposite Lillian Gish in the Griffith directed romantic film "True Heart Susie".