The Kandahar massacre, also called the Panjwai massacre, was a mass murder that occurred in the early hours of 11 March 2012, when United States Army Staff Sergeant Robert Bales murdered 16 Afghan civilians and wounded six others in the Panjwayi District of Kandahar Province, in the former Islamic Republic of Afghanistan. Nine of his victims were children, and 11 of the dead were from the same family. Some of the corpses were partially burned. Bales was taken into custody later that morning when he told authorities, "I did it".

The U.S. and International Security Assistance Force (ISAF) authorities apologized for the deaths. Afghan authorities condemned the act, describing it as "intentional murder". The National Assembly of Afghanistan passed a resolution demanding a public trial in Afghanistan. Still, then-U.S. Secretary of Defense Leon Panetta said the soldier would be tried under U.S. military law. Bales pleaded guilty on 5 June 2013 to 16 counts of premeditated murder in exchange for the prosecution not seeking a death sentence. At the time of the plea, he said he did not know why he committed the murders. On 23 August 2013, Bales was sentenced to life in prison without the possibility of parole.

United States authorities concluded that the killings were the act of a single individual. On 15 March 2012, an Afghan parliamentary probe team consisting of several members of the National Assembly of Afghanistan had speculated that up to 20 U.S. soldiers were involved in the killings. The team later said they could not confirm claims that multiple soldiers participated in the massacre.

Panjwai is the birthplace of the Taliban movement and has traditionally been a stronghold of the Taliban. It has been an area of heavy fighting and was the focus of a military surge in 2010, which brought a more than two-fold increase in airstrikes, night raids into Afghan homes, insurgent casualties, and a six-fold increase in special forces operations throughout Afghanistan.

Fighting in Panjwai and adjacent Zhari, Arghandab, and Kandahar districts was particularly intense. The conflict between the civilian population and U.S. forces was exacerbated by the wholesale destruction of some villages by U.S. forces, mass arrests, murder of civilians by rogue units, and high casualties from improvised explosive devices (IEDs). One of the families targeted in the Kandahar massacre returned to the area in 2011 after being displaced by the surge. Fearing the Taliban but encouraged by the U.S. government, the Army, and the Afghan government, they settled near the U.S. military base because they thought it would be a safe place to live.

Approximately three weeks before the incidents, Afghan–U.S. relations were strained by an incident where copies of the Quran were burnt at the Bagram Air Base. A couple of months before the shootings, U.S. Marines were videorecorded urinating on dead Taliban fighters.

The shooter, Robert Bales, was based at Joint Base Lewis-McChord (JBLM). The primary medical treatment facility at the base, Madigan Army Medical Center, has come under investigation for downgrading diagnoses of soldiers with PTSD to lesser ailments. Military support groups around the base have alleged that base commanders did not give returning troops sufficient time to recover before sending them on further deployments and that the base's medical unit was understaffed and overwhelmed by the numbers of returning veterans with deployment-related physical and psychological trauma.

Soldiers from the base have been linked to other atrocities and crimes. The 2010 Maywand District murders involved JBLM-based soldiers. Also in 2010, a recently discharged AWOL soldier from JBLM shot a police officer in Salt Lake City. In April 2011, a JBLM soldier killed his wife and 5-year-old son before killing himself. In January 2012, a JBLM soldier murdered a Mount Rainier National Park ranger. In two separate incidents, unrelated JBLM soldiers have been charged with waterboarding their children.