The Oklahoma City bombing was a domestic terrorist truck bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, United States, on April 19, 1995, the second anniversary of the end to the Waco siege. The bombing was the deadliest act of terrorism in U.S. history before the September 11 attacks in 2001, and it remains the deadliest act of domestic terrorism in U.S. history.

Perpetrated by anti-government extremists Timothy McVeigh and Terry Nichols, the bombing occurred at 9:02 a.m. and killed 168 people, injured 680, and destroyed more than one-third of the building, which had to be demolished. The blast destroyed or damaged 324 other buildings and caused an estimated $652 million worth of damage. Local, state, federal, and worldwide agencies engaged in extensive rescue efforts in the wake of the bombing. The Federal Emergency Management Agency (FEMA) activated 11 of its Urban Search and Rescue Task Forces, consisting of 665 rescue workers.

Within 90 minutes of the explosion, McVeigh was stopped by Oklahoma Highway Patrolman Charlie Hanger for driving without a license plate and arrested for illegal weapons possession. Forensic evidence quickly linked McVeigh and Nichols to the attack; Nichols was arrested, and within days, both were charged. Michael and Lori Fortier were later identified as accomplices. McVeigh, a veteran of the Gulf War and a sympathizer with the U.S. militia movement, had detonated a Ryder rental truck full of explosives he parked in front of the building. Nichols had assisted with the bomb's preparation. Motivated by his dislike for the U.S. federal government and its handling of Ruby Ridge in 1992 and the Waco siege in 1993, McVeigh timed his attack to coincide with the second anniversary of the fire that ended the siege in Waco. Though not confirmed to be a direct connection to the bombing, white supremacist Richard Snell previously expressed a desire to blow up the Murrah Federal Building 12 years before the bombing took place.

The official FBI investigation, known as "OKBOMB", involved 28,000 interviews, 3,200 kg of evidence, and nearly one billion pieces of information. When the FBI raided McVeigh's home, they found a telephone number that led them to a farm where McVeigh had purchased supplies for the bombing. The bombers were tried and convicted in 1997. McVeigh was executed by lethal injection on June 11, 2001, at the U.S. federal penitentiary in Terre Haute, Indiana. Nichols was sentenced to life in prison in 2004. In response to the bombing, the U.S. Congress passed the Antiterrorism and Effective Death Penalty Act of 1996, which limited access to habeas corpus in the United States, among other provisions. It also passed legislation to increase the protection around federal buildings to deter future terrorist attacks.