Louis III, Count of Rieneck

Louis III, Count of Rieneck (c. 1236 – 1289/1291), was the eldest son of Count Louis of Rieneck (died 1243) and Adelaide of Henneberg. In 1243 Rothenfels Castle on the Main passed to him through his wife Udelhilt, heiress of Albert II of Grumbach, adding lands that nearly doubled Rieneck's territory.

From 1257 his Rothenfels line bore a standing swan on its helmet, proclaiming descent from the Swan Knight Lohengrin. His children included counts Thomas and Louis V, and Elizabeth, married in 1272 to Ulrich I of Hanau.