Stanley Allen McChrystal (born August 14, 1954) is a retired United States Army General. His last assignment was as Commander, International Security Assistance Force (ISAF) and Commander, U.S. Forces Afghanistan (USFOR-A). He previously served as Director, Joint Staff from August 2008 to June 2009 and as Commander, Joint Special Operations Command from 2003 to 2008, where he was credited with the death of Abu Musab al-Zarqawi, leader of Al-Qaeda in Iraq, but also criticized for his alleged role in the cover-up of the Pat Tillman friendly fire incident. McChrystal was reportedly known for saying and thinking what other military leaders were afraid to; this was one of the reasons cited for his appointment to lead all forces in Afghanistan. He held the post from June 15, 2009, to June 23, 2010.

Following unflattering remarks about Vice President Joe Biden and other administration officials attributed to McChrystal and his aides in a Rolling Stone article, McChrystal was recalled to Washington, D.C., where President Barack Obama accepted his resignation as commander in Afghanistan. His command of the International Security Assistance Force in Afghanistan was immediately assumed by the deputy commander, British General Sir Nicholas "Nick" Parker, pending the confirmation of a replacement. Obama named General David Petraeus as McChrystals replacement; Petraeus was confirmed by the Senate and officially assumed command on June 30. Days after being relieved of his duties in Afghanistan, McChrystal announced his retirement.

In 2010, after leaving the Army, McChrystal joined Yale University as a Jackson Institute for Global Affairs senior fellow. He teaches a course entitled "Leadership," a graduate-level seminar with some spots reserved for undergraduates. The course received 250 applications for 20 spots in 2011 and is being taught for a third time in 2013.

McChrystal co-founded and is a partner at the McChrystal Group LLC, an Alexandria, Virginia-based consulting firm.

McChrystals memoir, My Share of the Task, published by Portfolio of the Penguin Group, was released on January 7, 2013. The autobiography had been scheduled to be released in November 2012, but was delayed due to security clearance approvals required from the Department of Defense.

McChrystal is the son of Mary Gardner Bright and Major General Herbert J. McChrystal, Jr., and was the fourth child in a family of five boys and a girl, all of whom would serve in the military or marry military spouses. His older brother, Colonel Scott McChrystal, is a retired Army chaplain, and is the endorsing agent for the Assemblies of God.

McChrystal married his wife Annie in April 1977, and the couple has one adult son, Sam.