Ludwig I or Louis I was King of Bavaria from 1825 until the 1848 revolutions in the German states. When he was crown prince, he was involved in the Napoleonic Wars. As king, he encouraged Bavaria's industrialization, initiating the Ludwig Canal between the rivers Main and the Danube. In 1835, the first German railway was constructed in his domain, between the cities of Fürth and Nuremberg, with his Bavaria joining the Zollverein economic union in 1834. After the July Revolution of 1830 in France, Ludwig's previous liberal policy became increasingly repressive; in 1844, Ludwig was confronted during the Beer riots in Bavaria. During the revolutions of 1848 the king faced increasing protests and demonstrations by students and the middle classes. On 20 March 1848, he abdicated in favour of his eldest son, Maximilian.

The King of Bavaria was a title held by the hereditary Wittelsbach rulers of Bavaria in the state known as the Kingdom of Bavaria from 1805 until 1918, when the kingdom was abolished. It was the second time Bavaria was a kingdom, almost a thousand years after the short-lived Carolingian kingdom of Bavaria.