Experten: Kan vara största IS-dådet sedan 2017

On the afternoon of 17 August 2017, 22-year-old Younes Abouyaaqoub drove a van into pedestrians on La Rambla street in Barcelona, Catalonia, Spain killing 13 people and injuring at least 130 others, one of whom died 10 days later on 27 August. Abouyaaqoub fled the attack on foot, then killed another person in order to steal the victim's car to make his escape. Nine hours after the Barcelona attack, five men thought to be members of the same terrorist cell drove into pedestrians in nearby Cambrils, killing one woman and injuring six others. All five of those attackers were shot and killed by police. The night before the Barcelona attack, an explosion occurred in a house in the Catalan town of Alcanar, destroying the building and killing two members of the terrorist cell, including the 40-year-old imam thought to be the mastermind. The home had more than 120 gas canisters inside which police believe the cell was attempting to make into one large bomb (or three smaller bombs to be placed in three vans that they had rented) but which they accidentally detonated. The Prime Minister of Spain, Mariano Rajoy, called the attack in Barcelona a jihadist attack. Amaq News Agency attributed indirect responsibility for the attack to the Islamic State. The attacks were the deadliest in Spain since the March 2004 Madrid train bombings and the deadliest in Barcelona since the 1987 Hipercor bombing. Younes Abouyaaqoub, the driver of the van in the Barcelona attack, was killed by police in Subirats, a town 31 kilometres (19 mi) west of Barcelona on 21 August. A 2022 statement by former Spanish police commissioner José Manuel Villarejo appeared to suggest in the Spanish High Court that the Spanish National Intelligence Service was aware of the attacks. Others have dismissed this statement as a conspiracy theory.

The following is a list of major terrorist attacks and arrests that have been connected to or have been claimed in reliable sources to be inspired by the Islamic State (IS), also known by other names. Islamic State's predecessor organization, Islamic State of Iraq (ISI) was established in October 2006, after the dissolution of the insurgent groups fighting under the coalition of Mujahideen Shura Council. Under the leadership of its first Emir Abu Omar al-Baghdadi, ISI was in the Iraqi insurgency against American occupation. After the withdrawal of U.S. troops from Iraq, ISI, then-led by Abu Bakr al-Baghdadi, continued its insurgency against the Iraqi government. In April 2013, the group officially changed its name to "Islamic State of Iraq and Levant" and established a presence in Syria. Between June 2014, when the group self-proclaimed itself to be the Islamic State, and February 2018, IS has often made claims of responsibility over 140 terrorist attacks in 29 countries outside Syria and Iraq, that were "conducted or inspired" by the group, while the evidences of those claims are not verified. Hundreds of other attacks were also carried out since 2018.