Louis II the Younger (825 – Ghedi 12 August 875) is the King of Italy and Roman Emperor from 844, co-ruling with his father Lothair I until 855, after which he rules alone.

Louis's usual title is imperator augustus ("august emperor"), but he uses imperator Romanorum after his conquest of Bari in 871, which leads to poor relations with Byzantium.

He is called imperator Italiae ("emperor of Italy") in West Francia while the Byzantines call him Basileus Phrangias ("Emperor of the Franks").

The chronicler Andreas Bergomatis, who is the most important source for Louis's activities in southern Italy, notes that "after his death a great tribulation came to Italy."

(Post cuius obitum magna tribulatio in Italia advenit.

Andreas, Historia in Georg Waitz (ed.

), MGH SS rerum Langobardicarum (Hannover: 1878), 222–30, §18.)