Ivan VI Antonovich of Russia (Ioann Antonovich; Russian: Иоанн VI; Иоанн Антонович; 23 August [O.S. 12 August] 1740 – 16 July [O.S. 5 July] 1764) was nominally Emperor of Russia in 1740-41. He was only two months old when he was proclaimed Emperor and his mother named regent. Scarcely a year later his first cousin twice-removed, Elizabeth, seized the throne in a coup, ruling thereafter as Empress of Russia. Ivan and his parents were imprisoned far from the capital and spent the rest of their lives in captivity. After more than twenty years as a prisoner, Ivan was killed by his guards when some army officers (unknown to Ivan) attempted to free him. His surviving siblings, who had been born in prison, then were released into the custody of their aunt, the Queen of Denmark, but none could live normally after a lifetime of confinement.

Ivan was born on 12/23 August 1740 at Saint Petersburg, the eldest child of Duke Anthony Ulrich of Brunswick-Lüneburg by his wife, Duchess Anna Leopoldovna of Mecklenburg-Schwerin, the only niece of the childless Empress Anna of Russia, and the only granddaughter of Tsar Ivan V. She had lived in Russia almost all her life, and her husband had also made his home in that country, in the expectation that they or their progeny would inherit the throne upon the death of the empress.

This expectation was fulfilled within two months of the birth of their first-born child. On 5 October 1740 the infant Ivan was adopted by his grandaunt (who was on her deathbed) and declared her heir apparent. The empress also declared that her longtime lover and advisor, Ernst Johann von Biron, duke of Courland, would serve as regent until Ivan came of age. Indeed the desire to ensure that her lover would enjoy power and influence after her death was the primary reason the dying empress chose to name as her heir the infant rather than his mother.

...
Wikipedia