Imam Shamil (Arabic: الشيخ شامل, romanized: al-Šaykh Šāmil; Avar: Шейх Шамил, romanized: Sheykh Shamil; Chechen: имам Шемал, romanized: imam Shemal; Kumyk: Шамил, romanized: Şamil; Russian: Имам Шамиль; 26 June 1797 – 4 February 1871) was the political, military, and spiritual leader of North Caucasian resistance to Imperial Russia in the 1800s, the third Imam of the Caucasian Imamate (1840–1859), and a Sunni Muslim sheikh of the Naqshbandi Sufis.

Imam Shamil was born in 1797 into an Avar Muslim family. He was born in the small village (aul) of Gimry (present-day Dagestan, Russia). Some sources state that he had a paternal Kumyk lineage. He was originally named Ali, but following local tradition, his name was changed to Shamuyil (Arabic: شمویل, equivalent to Samuel) when he became ill. This name is pronounced Shamil in the Caucasus, and contemporary sources called him by this name (either شامل Shāmil or شمیل Shamīl in Arabic), although in his writings he always used the form Shamuyil. His father, Dengau, was a landlord, and this position allowed Shamil and his close friend Ghazi Muhammad to study many subjects, including Arabic and logic.^{[citation needed]}

Shamil grew up at a time when the Russian Empire was expanding into the territories of the Ottoman Empire and Qajar Iran (see Russo-Persian War (1804–1813) and Russo-Turkish War (1806–1812)). Many Caucasian peoples united in resistance to Russian imperial aspirations in what became known as the Caucasian War (1817-1864). Earlier leaders of Caucasian resistance included Hadji-Dawud, Sheikh Mansur and Ghazi Mollah. Shamil, a childhood friend of the Mollah, would become his disciple and counsellor.

Shamil had multiple wives, including one of Armenian ethnicity born in Russia named Anna Ivanovna Ulukhanova (or Ulykhanova; 1828-1877). Captured in a raid in 1840, she married Shamil six years later. She converted to Islam as a teenager and adopted the name Shuanet. Shuanet remained loyal to Shamil even after his capture and exile to Russia. After the death of Shamil (1871) she moved to the Ottoman Empire, where the sultan assigned her a pension.

In 1832, Ghazi Mollah died at the battle of Gimry, and Shamil was one of only two murids to escape, but he sustained severe wounds. During this fight he was stabbed with a bayonet. After reportedly jumping from an elevated stoop "clean over the heads of the very line of soldiers about to fire on him ... [he landed] behind them, whirling his sword in his left hand he cut down three of them, but was bayoneted by the fourth, the steel plunging deep in his chest. He seized the bayonet, pulled it out of his own flesh, cut down the man, and with another superhuman leap, cleared the wall and vanished in the darkness". He went into hiding and both Russia and murids assumed him dead. Once recovered, he emerged from hiding and rejoined the murids, led by the second Imam, Hamzat Bek. He would wage unremitting warfare on the Russians for the next quarter century and become one of the legendary guerrilla commanders of the century. When Hamzat Bek was killed in 1834, Shamil took his place as the prime leader of the Caucasian resistance and the third Imam of the Caucasian Imamate.

In June–August 1839, Shamil and his followers, numbering about 4000 men, women and children, found themselves under siege in their mountain stronghold of Akhoulgo, nestled in the bend of the Andi Koysu, about ten miles east of Gimry. Under the command of General Pavel Grabbe, the Russian army trekked through lands devoid of supplies because of Shamil's scorched-earth strategy. The geography of the stronghold protected it from three sides, adding to the difficulty of conducting the siege. Eventually the two sides agreed to negotiate. Complying with Grabbe's demands, Shamil gave his son, Jamaldin, in a sign of good faith, as a hostage. Shamil rejected Grabbe's proposal that Shamil command his forces to surrender and for him to accept exile from the region. The Russian army attacked the stronghold, after 2 days of fighting, the Russian troops had secured it. Shamil escaped the siege during the first night of the attack. Shamil's forces had been broken and many Dagestani and Chechen chieftains proclaimed loyalty to the Tsar. Shamil fled Dagestan for Chechnya. There, he made quick work of extending his influence over the clans.

Shamil was effective at uniting the many, quarrelsome Caucasian tribes to fight against the Russians, by the force of his charisma, piety and fairness in applying Sharia law. One Russian source commented on him as "a man of great tact and a subtle politician." He believed the Russian introduction of alcohol in the area corrupted traditional values. Against the large regular Russian military, Shamil made effective use of irregular and guerrilla tactics. In 1845, an 8000-10000 strong column under the command of Count Mikhail Vorontsov followed the Imamate's forces into the forests of Chechnya. The Imamate's forces surround the Russian column, destroying it. This destroyed Vorontsov's attempt to cut away Chechnya from the Imamate, which was his plan.

Shamil is showing great activity this year and he is forced to do this, since we ... are taking measures that must sooner or later ... destroy his influence and tear away the Chechens from him, without which he will be nothing.