Lavr Georgiyevich Kornilov (Russian: Лавр Гео́ргиевич Корни́лов, IPA: [ˈlavr ɡʲɪˈorɡʲɪjɪvʲɪtɕ kɐrˈnʲiləf]; 30 August [O.S. 18 August] 1870 – 13 April 1918) was a Russian military intelligence officer, explorer, and general in the Imperial Russian Army during World War I. He served as Supreme Commander of the Russian Army and as the military leader of the Whites in the Russian Civil War. He is particularly remembered for the Kornilov affair, an unsuccessful coup d’etat against the Provisional Government led by Alexander Kerensky. The event became a significant turning point in the Russian Revolution, strengthening the Bolsheviks' position and influence.

Born in Ust-Kamenogorsk, Kornilov began his military career after graduating from the Mikhailovsky Artillery School and the General Staff Academy. He distinguished himself during the Russo-Japanese War and later served as a military attaché in Qing China. During World War I, Kornilov commanded the 48th Infantry Division and gained recognition for his daring escape from Austrian captivity in 1915. His successes on the Eastern Front elevated him to prominence, leading to his appointment as Supreme Commander during the revolutionary upheaval of 1917.

After the Bolshevik seizure of power in November 1917, Kornilov emerged as a key figure in the White movement. Following his escape from detention after the Kornilov Affair, he co-founded the Volunteer Army and led its forces in southern Russia during the early stages of the Russian Civil War. Kornilov was killed in 1918 during the siege of Yekaterinodar. His legacy remains deeply contested, viewed by some as a patriot fighting for Russia's unity and by others as a reactionary figure whose actions exacerbated the nation’s descent into chaos.

One story relates how Kornilov was originally born as a Don Cossack Kalmyk named Lavga Deldinov and adopted in Ust-Kamenogorsk, Russian Turkestan (now Kazakhstan) by the family of his mother's brother, the Russian Cossack Khorunzhiy Georgy Nikolayevich Kornilov, whose wife was of Kazakh origin. But his sister wrote that he had not been adopted, had not been a Don Cossack, and that their mother had Polish and Altai Oirot descent. (Though their language was not a Kalmyk/Mongolian one, but because of their Asian race and their history in the Jungar Oirot (Kalmyk) state, Altai Oirots were called Altai Kalmyks by Russians. They were not Muslims or Kazakhs.) But Boris Shaposhnikov, who served with Pyotr Kornilov, the brother of Lavr, in 1903, mentioned the "Kyrgyz" ancestry of their mother—this name was usually used in reference to Kazakhs in 1903. Kornilov's Siberian Cossack father was a friend of Potanin (1835–1920), a prominent figure in the Siberian autonomy movement.

Kornilov entered military school in Omsk in 1885 and went on to study at the Mikhailovsky Artillery School in St. Petersburg in 1889. In August 1892 he was assigned as a lieutenant to the Turkestan Military District, where he led several exploration missions in Eastern Turkestan, Afghanistan and Persia, learned several Central Asian languages, and wrote detailed reports about his observations.

Kornilov returned to St. Petersburg to attend the Nikolayev General Staff Academy and graduated as a captain in 1897. Again refusing a posting at St. Peterburg, he returned to the Turkestan Military District, where he resumed his duties as a military intelligence officer. Among his missions at this post was an attempt at traveling incognito to British India in 1904, though he was quickly discovered and subsequently kept under close surveillance.

During the Russo-Japanese War of 1904–1905 Kornilov became the chief of staff of the 1st Infantry Brigade, and was heavily involved in the Battle of Sandepu (January 1905) and the Battle of Mukden (February/March 1905). He was awarded the Order of St. George (4th class) for bravery and promoted to the rank of colonel.

Following the end of the war, Kornilov served as military attache in China from 1907 to 1911. He studied the Chinese language, travelled extensively (researching data on the history, traditions and customs of the Chinese, which he intended to use as material for a book about life in contemporary China), and regularly sent detailed reports to the General Staff and Foreign Ministry. Kornilov paid much attention to the prospects of cooperation between Russia and China in the Far East and met with the future president of China, Chiang Kai-shek. In 1910 Kornilov was recalled from Beijing but remained in St. Petersburg for only five months before departing for western Mongolia and Kashgar to examine the military situation along China's border with Russia. On 2 February 1911 he became Commander of the 8th Infantry Regiment of Estonia and was later appointed commander of the 9th Siberian Rifle Division, stationed in Vladivostok.