Baron Pyotr Nikolayevich Wrangel (Russian: Пётр Николаевич Врангель [ˈpʲɵtr nʲɪkɐˈlajɪvʲɪtɕ ˈvranɡʲɪlʲ]; August 27 [O.S. August 15] 1878 – 25 April 1928) was a Russian military officer of Baltic German descent. A veteran of the Russo-Japanese War and World War I, he rose to become a commanding general in the anti-Bolshevik Volunteer Army during the Russian Civil War. In 1920, he became the last commander-in-chief of the White forces in Southern Russia, which he reorganized as the Russian Army.

After graduating as a mining engineer, Wrangel volunteered for service in the Russo-Japanese War, where he decided on a military career. A graduate of the Imperial General Staff Academy, he distinguished himself during World War I, becoming one of the first Russian officers to be awarded the Order of St. George for heroism. He rose to the rank of major general.

After the October Revolution, Wrangel joined the Volunteer Army in August 1918 and was given command of major cavalry formations. He became known for his aggressive leadership and battlefield successes in the northern Caucasus. In 1919, he captured the strategic city of Tsaritsyn but soon clashed with his superior, Anton Denikin, over the latter's Moscow Directive, a plan Wrangel considered strategically flawed. The growing rivalry led to his dismissal from command in December 1919.

Following Denikin's resignation in April 1920, Wrangel was elected commander-in-chief of the shattered White forces in Crimea. He established the Government of South Russia and attempted to win popular support with a wide-ranging series of reforms, including a radical land reform. After initial military successes against the Red Army, his forces were defeated, and he organized a mass evacuation from Crimea in November 1920, successfully evacuating over 145,000 people. In exile, he remained a leader of the White movement and founded the Russian All-Military Union (ROVS) in 1924. He is remembered as the last commander of the White Army, a more able administrator and strategist than his predecessors, who took command when the White cause was already considered lost.

Pyotr Wrangel was born in Novalexandrovsk, Kovno Governorate in the Russian Empire (now Zarasai, Lithuania) on 28 August 1878, the eldest of three brothers. He was a scion of the Wrangel family, a Baltic German noble house of Swedish origin that had served the rulers of Sweden, Prussia, Austria and Russia for over 700 years. The family produced seven field marshals, seven admirals, and dozens of generals. His ancestor, the Swedish Field Marshal Herman Wrangel, was the father of Carl Gustaf Wrangel, who built Skokloster Castle. By the nineteenth century, branches of the family had established themselves in the Russian Empire, including Baron Ferdinand von Wrangel, the explorer and governor-general of Alaska.

Pyotr's father, Baron Nikolai Egorovich Wrangel [ru], was a humanist, art connoisseur, and writer who had rebelled against the family's military tradition. Nikolai later wrote a memoir, From Serfdom to Bolshevism, detailing his life and experiences. Pyotr's mother, Maria Dimitrievna Dementieva-Maikova, was the daughter of an impoverished officer but was well-educated and interested in social reform. The family lived in a liberal, cultured atmosphere in Rostov-on-Don, where Nikolai was a director of several companies.

Following his father's wishes, Wrangel was sent to a civilian school. His father, interested in gold mining in Siberia, decided that Pyotr should become a mining engineer and enrolled him in the School of Mines in Saint Petersburg. A dutiful son, Wrangel studied diligently and graduated first in his class, receiving a gold medal. Before pursuing his engineering career, he was required to complete his compulsory military service. For the Wrangel family, this meant joining the prestigious Horse Guards, which his father described as the "Family Regiment".

He entered the army on 13 September 1901. Life in the Horse Guards appealed to him, and he decided to apply for a permanent commission. As with all Guards regiments, a commission required a ballot vote by the regiment's officers. According to his son, on the eve of the ballot, Wrangel celebrated his expected promotion and, on returning home, drew his sword and decapitated a row of young trees planted outside the residence of his senior colonel, the humorless Prince Troubetzkoy. The Prince ensured Wrangel was blackballed, and he left for Siberia to begin his engineering career, reconciled to his new life. He began work as a chemical engineer in eastern Siberia.