Birutė (died 1382) was the second wife of Kęstutis, Grand Duke of Lithuania, and mother of Vytautas the Great. There is very little known about Birutė's life, but after her death a strong cult developed among Lithuanians, especially in Samogitia.
Probably she was born near Palanga to a Samogitian or Curonian magnate family. The story of her marriage to Kęstutis became a romantic legend in Lithuania. Chronicles mention that Birutė was a priestess (Lithuanian: vaidilutė) and served the Pagan gods by guarding the sacred fire. When Kęstutis heard of her beauty, he visited the shire and asked her to marry him. She refused because she had promised the gods to guard her virginity until her death. Kęstutis then took her by force to Trakai and threw a big wedding. She and Kęstutis had three sons and three daughters. Vytautas, their first son, was born around 1350. This suggests that the marriage took place in 1349 or a bit earlier.
Historian S.C. Rowell suggests that a marriage to a pagan duchess rather than to an Orthodox duchess from Slavic lands helped to win pagan Lithuanian support after Kęstutis and his brother Algirdas deposed Jaunutis in 1345.
The circumstances surrounding Birutė's death are not entirely clear. Between 1381 and 1382 her husband Kęstutis waged a war against his nephew Jogaila who became the Grand Duke of Lithuania and signed a treaty with the Teutonic Knights against Kęstutis. Her husband was arrested and transported to the castle at Kreva. A week later Kęstutis was dead and some chronicles hint that he was murdered. In spite of the circumstances being unclear, one chronicle written by the Teutonic Knights briefly mentioned that Birutė was, for reasons of safety, moved to Brest, Belarus, where she drowned in fall of 1382 (likely in response to Vytautas escape from Kreva). However, there are no other sources that confirm or refute this claim. Thirty-five years later, a Samogitian delegation to the Council of Constance denied her murder, and another legend claimed that Birutė returned to the shrine where she had served earlier in Palanga, and resumed serving the gods until her death there circa 1389.