Louis III, Count of Looz (died 15 May 1243), also known as Ludwig (Latin Lodevicus) was Count of Loon and of Rieneck.
Arnold III however died childless, and Louis subsequently also became count in both Rieneck, now in Germany, and Loon, now in Belgium.
Loon eventually became a county of Louis III's younger brother Arnold IV, Count of Loon, and the division of the two counties became permanent.
Louis III had children and his descendants continued to be counts of Rieneck into the 16th century.
149–150) reports that Louis married Adelheid of Henneburg and they had the following children: