Louis III, Count of Looz (died 15 May 1243), also known as Ludwig (Latin Lodevicus) was Count of Loon and of Rieneck. He was the son of Gerard, Count of Rieneck (died 1216), and Cunegonde von Zimmern, who was in turn the son of another Count Gerard who was also count of both Rieneck and Loon (died 1191).

Upon the death of his father in 1216, and his uncles Louis II, Count of Loon,