Otto III, Duke of Bavaria
|Reign||3 February 1290 – 9 November 1312|
|Reign||6 December 1305 – 1308|
|Coronation||6 December 1305 (Székesfehérvár)|
|Spouse||Katharine of Habsburg
Agnes of Glogau
|Henry XV, Duke of Bavaria|
|House||House of Wittelsbach|
|Father||Henry XIII, Duke of Bavaria|
|Mother||Elizabeth of Hungary|
11 February 1261|
|Died||9 November 1312
Otto III of Bavaria (11 February 1261 – 9 November 1312), member of the Wittelsbach dynasty, was Duke of Lower Bavaria from 1290 to 1312 and disputably King of Hungary and Croatia between 1305 and 1307 as Béla V.
Otto succeeded his father in 1290 as duke of Lower Bavaria, together with his younger brothers, Louis III and Stephen I. He was in opposition to Habsburg and tried to regain Styria which Bavaria had lost in 1180. The Hungarian crown was offered to Otto who was a grandson of Béla IV of Hungary in 1301 but he did not accept before 1305.
In August 1305, his opponent, Wenceslaus III of Bohemia, who had inherited Bohemia from his father, renounced his claim to Hungary on behalf of Otto III. Otto arrived to Hungary soon and he was crowned with the Holy Crown of Hungary in Székesfehérvár by the Bishops of Veszprém and Csanád on 6 December. He named himself Béla V after his grandfather. However, Otto was not able to strengthen his rule. In the course of 1306, Otto's second opponent Charles of Anjou occupied Esztergom, Szepes/Spiš Castle, Zólyom/Zvolen and some other fortresses in the northern parts of the kingdom, and in the next year he also occupied Buda. In June 1307, Duke Otto III visited the powerful Voivode of Transylvania, Ladislaus Kán, but the latter arrested him. On 10 October 1307, the magnates presented at the assembly in Rákos proclaimed Charles king, but the most powerful aristocrats (Máté Csák, Amadé Aba and Ladislaus Kán) ignored him as well. At the end of the year, Ladislaus Kán set Otto free who then left the country, but the Voivode of Transylvania still denied to hand over the Holy Crown of Hungary to Charles, whose legitimacy could be questioned without the coronation with the Holy Crown.
Otto abdicated the Hungarian throne in 1308. Otto's involvement in Austrian and Hungarian affairs weakened his position in Bavaria and finally led to failure due to financial problems. In Hungarian historiography he is noted as an anti-king during the interregnum of 1301–1310.
During his presence in Hungary 1305–1308 Lower Bavaria was ruled by his brother Stephen I. Otto was succeeded in Lower Bavaria by his son Henry XV, who shared power with his cousins, Henry XIV and Otto IV, both sons of Stephen I. John I, a son of Henry XIV, was the last duke of Lower Bavaria before Louis IV, Holy Roman Emperor inherited the country and reunited the duchy in 1340.
Marriages and children 
- Henry of Wittelsbach (1280). Twin brother of Rudolph. Died within the year of his birth.
- Rudolph of Wittelsbach (1280). Twin brother of Henry. Died within the year of his birth.
Katharina died on 4 April 1282. Otto remained a widower for twenty-three years. On 18 May 1309, Otto married his second wife Agnes of Glogau. She was a daughter of Henry III, Duke of Silesia-Glogau, and Matilda of Brunswick-Lüneburg. They had two children:
- Agnes of Wittelsbach (1310–1360).
- Henry XV, Duke of Bavaria (28 August 1312 – 18 June 1333).
Otto died in Landshut.
|This section does not cite any references or sources. (August 2012)|
|Ancestors of Otto III, Duke of Bavaria|
- Historisches Lexikon Bayerns: Ungarisches Königtum Ottos III. von Niederbayern, 1305–1307 (Sarah Hadry)
- Cawley, Charles, Listing of Henry XIII along with his wife . The project "involves extracting and analysing detailed information from primary sources, including contemporary chronicles, cartularies, necrologies and testaments.", Foundation for Medieval Genealogy, retrieved August 2012
- A listing of descendants of Otto I, Count of Scheyern, including Henry XIII and his children
Otto III, Duke of BavariaBorn: 11 February}1261 9 November
|Duke of Lower Bavaria
|King of Hungary