Stephen III (1337 – 26 September 1413), called the Magnificent or the Fop (Stephan der Kneißl), was the Duke of Bavaria-Ingolstadt from 1375.
John II partitioned Bavaria as the result of his refusal to finance his brothers' expensive ambitions in the Italian court.
After the division of Bavaria, Stephen retained Bavaria-Ingolstadt, although he soon came to regard his share to be inferior to the other two Duchies.
After the deaths of both of his brothers, Stephen attempted to extend his Duchy, this time causing conflict with his nephews.
His final attempt in 1410 to reconquer Tyrol, which his father had ceded to the Grand Duchy of Habsburg was likewise unsuccessful.