Muhammad Umar Mujahid ( 1959 – 23 April 2013), commonly known as Mullah Omar or Muhammad Omar, was an Afghan militant leader who ruled Afghanistan as Supreme Leader from 1996 to 2001. He founded the Taliban in 1994 and served as its first supreme leader until his death in 2013. During the Third Afghan Civil War, the Taliban fought the Northern Alliance and took control of most of the country, establishing its First Islamic Emirate. Shortly after al-Qaeda carried out the September 11 attacks, the Taliban government was toppled by an American invasion of Afghanistan, prompting Omar to go into hiding; he successfully evaded capture by the American-led coalition before dying in 2013 from tuberculosis.

Born into a religious family in Kandahar, Omar was educated at local madrasas in Afghanistan. After Afghanistan was invaded by the Soviet Union in 1979, he joined the Afghan mujahideen to fight in the Soviet–Afghan War and he was trained by Amir Sultan Tarar. He served as an important rebel commander during several skirmishes, losing his right eye in an explosion. The Soviets eventually withdrew from the country in 1989 and Afghanistan's Soviet-backed Democratic Republic was toppled in 1992, triggering the Second Afghan Civil War. While initially remaining quiet and focused on continuing his studies, Omar became increasingly discontent with what he perceived as fasād in the country, ultimately prompting him to return to fighting in the Civil War.

In 1994, Omar, along with religious students in Kandahar, formed the Taliban, which emerged victorious against other Afghan factions by 1996. Omar led the Taliban to form a Sunni Islamic theocracy headed by the Supreme Council, known as the Islamic Emirate of Afghanistan, which strictly enforced sharia. While ruling between 1996 and 2001, the Taliban were widely condemned for committing massacres against civilians; discrimination against religious and ethnic minorities; banning women from school and most employment; and the destruction of cultural monuments, including the Buddhas of Bamiyan, which Omar personally ordered.

After al-Qaeda, which had been given sanctuary in Afghanistan by the Taliban, carried out the September 11 attacks against the United States in 2001, American president George W. Bush demanded that the Taliban extradite al-Qaeda's leader Osama bin Laden to the United States. The Taliban, under the leadership of Mullah Omar, refused to extradite him to the U.S. without concrete evidence linking him to the attacks, and they requested proof of his involvement in 9/11. The United States, however, had enough proof of him being in Afghanistan and under the Taliban's protection, and subsequently began the Global War on Terrorism and led a multinational invasion of Afghanistan in October 2001, greatly bolstered by the anti-Taliban Northern Alliance. By December 2001, the Taliban government had been ousted by the American-led coalition; Omar fled Kandahar, went into hiding in Zabul Province, and delegated operational control of the Taliban to his deputies. Under his command, the Taliban launched an insurgency against the new Afghan government and the coalition. Although Omar was the subject of a decade-long international manhunt, he remained in hiding for the rest of his life. He died in 2013, reportedly due to tuberculosis, which was not revealed publicly until 2015. In 2021, the Taliban deposed the Afghan government and regained power following the fall of Kabul.

Omar remains a largely popular figure amongst the Taliban, who view him as a key freedom fighter who defended Afghanistan's Islamic principles – first against the Soviet empire and later against the Western world. Others have criticised him for his method of governance and his religious dogmatism.

Muhammed Omar was born between 1950 and 1962 into a poor and large Pashtun family in the village of Chah-i-Himmat in Khakrez of Kandahar, Kingdom of Afghanistan. He came from a line of Islamic scholars and teachers. At 1.98 m (6 ft 6 in) tall, he was the tallest boy in his family.

His father was Mawlawi Ghulam Nabi, his grandfather Mawlawi Muhammad Rasool, and his great-grandfather Mawlawi Baz Muhammad. They were of the Tomzi clan of the Hotak tribe, which is part of the larger Ghilji tribal confederation of the Pashtuns. His father, born in Khakrez District, was a poor, landless itinerant teacher who taught the Quran to village boys and received alms from their families. He died when Omar was three years old, according to Omar's own words, or five years old, according to the Taliban biography. Thereafter Omar was raised by his uncles. One of his father's brothers, Maulawi Muzafer, married Omar's widowed mother, as was often done in rural Afghanistan.

The family moved to the village of Dehwanawark, several miles from the town of Deh Rawood, in the poor Deh Rawood District in Uruzgan Province, where the uncle was a religious teacher. According to former Afghan president Hamid Karzai, "Omar's father was a local religious leader, but the family was poor and had absolutely no political links in Kandahar or Kabul. They were essentially lower middle class Afghans and were definitely not members of the elite."^{[citation needed]}