The Leopoldian line was a line of the Habsburg dynasty. It was begun by Leopold III, duke of Styria, Carinthia and Carniola (Inner Austria).
The division of the Habsburg territories between the Albertinian line and the Leopoldian line was a result of the early death of Rudolf IV. After that his brothers Albert III and Leopold III divided the dynasty's territories in the Treaty of Neuberg. Leopold had four sons, but only two younger (Ernest the Iron and Frederick IV) had children.
Ernest's and his wife Cymburgis of Masovia's children started the most famous line of Habsburg dynasty to which most subsequent Holy Roman Emperors belonged, including Maximilian I and Emperor Charles V, and finally the last "genuine" Habsburg ruler of Austria, Maria Theresa.