Holstein-Gottorp or Schleswig-Holstein-Gottorp was a duchy consisting of areas within Schleswig and Holstein, in present-day Denmark and Germany. From 1544, when it was ceded to Adolf , the brother of King Christian III of Denmark, the Dukes of Holstein-Gottorp shared the rule of Schleswig and Holstein with the Kings of Denmark. As such, they were often the clients of the Swedes, the great enemies to the dames, and Duke Friedrich IV married the daughter of King Charles XI of Sweden. Following the Great Northern War, the Dukes had to cede their lands in Schleswig to the Danes. Duke Karl Friedrich, however, fled to the court of Peter the Great of Russia, and for some time the Russians intrigued to restore Karl Friedrich to his lands in Schleswig. Karl Friedrich himself was married to Grand Duchess Anna, Peter's daughter. Although Peter's successors abandoned his policy of backing the pretensions of the Duke of Holstein-Gottorp, from this marriage was born Karl Peter Ulrich, who succeeded to Holstein-Gottorp in 1739, and became heir to the Russian throne upon the accession of his aunt Elisabeth in 1741.

Although Karl Peter Ulrich, who acceded the Russian throne as Peter III in 1762, was very interested in regaining his lands in Schleswig from the Danes, he was soon overthrown. His successor, his son Paul, was under the regency of his mother Catherine the Great, who in 1773 agreed with the Danes for her son's abdication of his rights in Schleswig-Holstein in favor of the Prince-Bishop of Lübeck, representative of a younger branch, and to a trade which would allow the Danes to take over the Holstein-Gottorp lands, giving the Prince-Bishop the County of Oldenburg in exchange.

The dynastic policy of the Dukes of Holstein-Gottorp resulted in their ruling Sweden from 1751 until 1818 and Russia briefly in 1762 and then again from 1796 until 1917.

Dukes of Holstein-Gottorp

• 1544-1586 : Adolf
• 1586-1587 : Friedrich II
• 1587-1590 : Philipp
• 1590-1616 : Johann Adolf
• 1616-1659 : Friedrich III
• 1659-1694 : Christian Albrecht
• 1694-1702 : Friedrich IV
• 1702-1739 : Karl Friedrich
• 1739-1762 : Karl Peter Ulrich (later Peter III of Russia)
• 1762-1773 : Paul (later Paul I of Russia)