Lower Bavaria (German: Niederbayern) is one of the seven administrative regions of Bavaria, Germany, located in the east of the state.

Lower Bavaria is subdivided into two regions (Planungsverband) - Landshut and Donau-Wald. Recent election results mark it as the most conservative part of Germany, generally giving huge margins to the CSU. This part of Bavaria includes the Bavarian Forest, a well-known tourist destination in Germany, and the Lower Bavarian Upland.

The duchy of Lower Bavaria was created for the first time with the First Bavarian partition in 1255 under duke Henry but there was no exact identity with the current territory. After the reunification in 1340 Bavaria was divided again in 1349, in 1353 Bavaria-Straubing and Bavaria-Landshut were created in Lower Bavaria. In 1505 Bavaria was irrevocable reunited. In 1837 king Ludwig I of Bavaria created the district of Lower Bavaria.

Bavaria, formally the Free State of Bavaria (German: Freistaat Bayern, pronounced [ˈfʁaɪʃtaːt ˈbaɪ.ɐn] ( listen)), is a state of Germany, located in the southeast of Germany. With an area of 70,548 square kilometres (27,200 sq mi), it is the largest state by area, forming almost 20% of the total land area of Germany. Bavaria is Germany's second most populous state (after North Rhine-Westphalia), with 12.5 million inhabitants, more than any of the three sovereign states on its borders. Bavaria's capital is Munich.

One of the oldest states of Europe, it was established as a duchy in the mid first millennium. In the 17th century, the Duke of Bavaria became a Prince-elector of the Holy Roman Empire. The Kingdom of Bavaria existed from 1806 to 1918, and Bavaria has since been a free state (republic). Modern Bavaria also includes parts of the historical regions of Franconia and Swabia.

The Bavarians emerged in a region north of the Alps, originally inhabited by the Gauls, which had been part of the Roman provinces of Raetia and Noricum. The Bavarians spoke Old High German but, unlike other Germanic groups, probably did not migrate from elsewhere. Rather, they seem to have coalesced out of other groups left behind by Roman withdrawal late in the 5th century. These peoples may have included the Celtic Boii, some remaining Romans, Marcomanni, Allemanni, Quadi, Thuringians, Goths, Scirians, Rugians, Heruli. The name "Bavarian" ("Baiuvarii") means "Men of Baia" which may indicate Bohemia, the homeland of the Celtic Boii and later of the Marcomanni. They first appear in written sources c. 520. Saint Boniface completed the people's conversion to Christianity in the early-8th century. Bavaria was, for the most part, unaffected by the Protestant Reformation.