The 2008 Mumbai attacks, colloquially known as 26/11, were a coordinated series of twelve Islamic terrorist attacks carried out in Mumbai, Maharashtra, India, from 26 to 29 November 2008, by ten members of the Lashkar-e-Taiba. A total of 175 people died, including nine of the attackers, and more than 300 were injured.

The attackers arrived in Mumbai via the Arabian Sea. They departed from Karachi on a Pakistani cargo vessel, hijacked an Indian fishing trawler on the way, and ended their journey to South Mumbai's coastline on inflatable boats. Eight of the attacks were mass shootings in South Mumbai at Chhatrapati Shivaji Terminus, Trident Hotel, Taj Mahal Palace Hotel, Leopold Cafe, Cama Hospital, Nariman House, Metro Big Cinemas, and in a lane behind St. Xavier's College and the headquarters of The Times of India. In addition to the mass shootings, an explosion occurred at Mazagaon, in Mumbai's port area, and in a taxi at Vile Parle. By the early morning of 28 November, all sites except for the Taj Hotel had been secured by the Mumbai Police and security forces. On 29 November, India's National Security Guards conducted Operation Black Tornado to flush out the remaining terrorists; it culminated in the death of the last remaining terrorists at the Taj Hotel and ended the attacks.

Before his execution in 2012, Ajmal Kasab, the sole surviving attacker captured by the Mumbai Police, stated and confessed that the terrorists were members of the Lashkar-e-Taiba and were controlled from Pakistan, corroborating initial claims from the Indian government. Although initially denying the claims, Pakistan later confirmed that the sole surviving perpetrator of the attacks was a Pakistani citizen. The subsequent capture and interrogation of David Headley, a Pakistani-American DEA informer, and Tahawwur Rana, a Canadian citizen of Pakistani origin and a former Pakistan Army captain, who was Headley's partner, pointed to the involvement of rogue officials of the Pakistan Army and ISI in the terrorist attacks, who provided support to Lashkar-e-Taiba. The capture of Zabiuddin Ansari aka Abu Hamza in July 2012, an Indian national radicalised by Lashkar-e-Taiba, provided further clarity to the plot.

On 9 April 2015, the foremost suspected ringleader of the attacks, Zakiur Rehman Lakhvi, was released on bail in Pakistan and disappeared. He evaded capture for years, until being arrested again in Lahore on 2 January 2021. In 2018, former Pakistani prime minister Nawaz Sharif questioned the Pakistani government's allowing men who had committed the attacks to cross into India. In 2022, one of the masterminds of the attack, Sajid Mir —who the Pakistani government had earlier said was dead — was convicted for funding terrorist activities by an anti-terrorism court in Pakistan and sentenced to 15 years in prison. Consequently, several masterminds such as LeT founder Hafiz Saeed and Zakiur Rehman Lakhvi, were convicted for terror financing in 2021–22, as Pakistan went into an economic crisis after the Financial Action Task Force (FATF) threatened the government of Pakistan to be put in the FATF Blacklist for failure to comply on money laundering and financing of terrorism.

Known as one of the deadliest terrorist attacks in Mumbai and across India, the 2008 attacks caused extensive property damage estimated at over $1 billion through fire, grenade attacks, and gunfire; although the human casualties were lower than in the 2006 Mumbai train bombings, which were also carried out by Lashkar-e-Taiba and killed 209 people while injuring more than 700, the attacks had a significant impact on the city’s infrastructure and security measures. The attacks strained diplomatic relations between India and Pakistan, and made a huge impact on law enforcement and security officials to deal with such scenarios in the future. The attacks also caused a major political impact on the then ruling government led by the United Progressive Alliance, as the same year, several other cities suffered from Islamic terrorism, which were also perpetrated by Pakistani terror groups.

Many terrorist attacks had occurred in Mumbai since the 13 coordinated bomb explosions that killed 257 people on 12 March 1993. The 1993 attacks were carried out as revenge for the earlier Bombay riots, in which many Muslims were killed. Between March 1993 and July 2006 Mumbai city saw 12 notable incidents of bomb attacks resulting in the death of 516 people and injuries to 1952. Whereas all of these were bomb attacks, the November 2008 Mumbai attacks were fidayeen or suicide attacks.

On 6 December 2002, a blast in a BEST bus near Ghatkopar station killed two people and injured 28. The bombing occurred on the 10th anniversary of the demolition of the Babri Mosque in Ayodhya. A bicycle bomb exploded near the Vile Parle station in Mumbai, killing one person and injuring 25 on 27 January 2003, a day before the visit of the Prime Minister of India Atal Bihari Vajpayee to the city. On 13 March 2003, a day after the 10th anniversary of the 1993 Bombay bombings, a bomb exploded in a train compartment near the Mulund station, killing 10 people and injuring 70. On 28 July 2003, a blast in a BEST bus in Ghatkopar killed 4 people and injured 32. On 25 August 2003, two bombs exploded in South Mumbai, one near the Gateway of India and the other at Zaveri Bazaar in Kalbadevi. At least 44 people were killed and 150 injured. On 11 July 2006, seven bombs exploded within 11 minutes on the Suburban Railway in Mumbai, killing 209 people, including 22 foreigners and more than 700 injured. According to the Mumbai Police, the bombings were carried out by Lashkar-e-Taiba (LeT) and Students Islamic Movement of India (SIMI).

A group of men said to number between 24 and 26 received training in marine warfare at a remote camp in mountainous Muzaffarabad in Pakistan.^[why?] Part of the training was said to have taken place on the Mangla Dam reservoir in Pakistan.