Mindaugas (also known as Mindowe) (c.1203 - 1263) ruled Lithuania as grand duke from c.1236 and as the country's sole king from 1253 until his death.

He and his wife Martha were baptized around 1252 by the bishop of Kulm (now Chelmno) in the presence of the Master of the Teutonic Order. A member of the Order named Christian was consecrated as first bishop of Lithuania.

The Baltic peoples continued to resist conversion to Christianity, and after defeat by pagan forces in 1260, Mindaugas renounced Christianity. He was killed by his nephew Traniate, after which the country relapsed into paganism until the conversion (1386) of grand duke Jagiello.

Only with Gediminas, grand duke from 1316, did Lithuania's revival begin. While Lithuanian grand dukes from Jagiello onward reigned also as kings of Poland, their titles remained separate, and Mindaugas remained the only king of Lithuania.