Louis I (Latin Ludovicus, German Ludwig, Dutch Lodewijk; died 11 August 1171) was the Count of Loon, now in modern Belgium, and Burgrave of Mainz, in Germany.

He was the son of Arnold II, Count of Looz, and his wife whose name may have been Adeleide or Agnes.

Arnold II died in 1139, and Louis was his heir, appearing that year as count of Rieneck.

[3][4] Agnes commissioned Hendrik van Veldeke to write his "Life of Saint Servatius".

However, Gilles, Count of Duras, successfully called in the help of the abbey and citizens of Sint-Truiden and together they defeated Louis' army.