Peter III Fyodorovich was Emperor of Russia from 5 January 1762 until 9 July of the same year, when he was overthrown by his wife, Catherine II. He was born in the German city of Kiel as Charles Peter Ulrich of Schleswig-Holstein-Gottorp, but he was a grandson of Peter the Great and a great-grandson of Charles XI of Sweden.

Charles Frederick, Duke of Schleswig-Holstein-Gottorp was a Prince of Sweden and Duke of Schleswig-Holstein-Gottorp and an important member of European royalty. His dynasty, the Dukes of Schleswig-Holstein-Gottorp, were a cadet branch of the ancient House of Oldenburg, which at that time was ruling Denmark-Norway. His mother was a sister of Charles XII of Sweden. Charles Frederick married a daughter of Peter the Great and became the father of the future Peter III of Russia. As such, he is the progenitor of the Russian imperial house of Holstein-Gottorp-Romanov and the patrilineal ancestor of all Russian emperors starting with Peter III, except for Catherine II.