Louis II (825-875), also known as Louis of Italy and Louis the Younger, was the eldest son of Emperor Lothair I, who he co-ruled with until 855, after which he inherited the imperial throne and ruled alone. Louis II was also King of Italy, and governed the kingdom before his ascension to emperor.

When his father died and his lands were divided amongst his sons, Louis was angry that he obtained no territory outside of Italy. Allying himself with his uncle, Louis the German, he fought against his own brother Lothair, King of Lotharingia, as well as his other uncle, King Charles the Bald, in 857. He reconciled with his brother in 858, and received the Kingdom of Provence in 863 after the death of his brother Charles. Louis had to deal with turbulence and chaos in Italy, as well as with Saracens ravaging its southern provinces, procuring the aid of Byzantine emperor Basil.

Louis was betrayed and imprisoned by one of his own nobles, Adelchis, Prince of Benevento, in 871, but was freed a month later due to fresh Saracen incursions. He unsuccessfully tried to punish Adelchis for his imprisonment, but had better luck against the Saracens. He eventually died in 875, naming his cousin Carloman as his successor.