Omar Ahmed Khadr (born September 19, 1986) is the fourth child in the Canadian Khadr family. He was captured by American forces at the age of 15 following a four-hour firefight with militants in the village of Ayub Kheyl, Afghanistan. He has spent six years in the Guantanamo Bay detention camps charged with war crimes and providing support to terrorism after allegedly throwing a grenade that killed a US soldier.

A Canadian citizen born in Toronto, he is the youngest prisoner held in the Guantanamo Bay detention camp by the United States and has been frequently referred to as a child soldier. The only Western citizen remaining in Guantanamo, Khadr is unique in that Canada has refused to seek extradition or repatriation despite the urgings of Amnesty International, UNICEF, the Canadian Bar Association and other prominent organisations. In April 2009, the Federal Court of Canada ruled that international law made it obligatory for the government to immediately demand Khadr's return. In August 2009, Ottawa said it would appeal the decision to Canada's Supreme Court. The Supreme Court plans to rule on the appeal on September 4 2009.

Khadr was the only person charged under the 2006 Military Commissions Act who did not boycott the Guantanamo proceedings. In February 2008, the Pentagon accidentally released documents that revealed that although Khadr was present during the firefight, there was no other evidence that he had thrown the grenade. In fact, military officials had originally reported that another of the surviving militants had thrown the grenade just before being killed. Canadian authorities also determined that Khadr had little knowledge of his father's alleged activities, since "he was out playing or simply not interested".