Hezbollah (; Arabic: حزب الله Ḥizbu 'llāh, lit. "Party of Allah" or "Party of God", also transliterated Hizbullah or Hizballah, among others) is a Lebanese Shia Islamist political party and militant group, led by its Secretary-General Hassan Nasrallah since 1992. Hezbollah's paramilitary wing is the Jihad Council, and its political wing is the Loyalty to the Resistance Bloc party in the Lebanese Parliament.

After the Israeli invasion of Lebanon in 1982, the idea of Hezbollah arose among Lebanese clerics who had studied in Najaf, and who adopted the model set out by Ayatollah Khomeini after the Iranian Revolution in 1979. The organization was established as part of an Iranian effort, through funding and the dispatch of a core group of Islamic Revolutionary Guard Corps (pasdaran) instructors, to aggregate a variety of Lebanese Shia groups into a unified organization to resist the Israeli occupation and improve the standing and status of the long marginalised and underrepresented Shia community in that country. A contingent of 1,500 pasdaran instructors arrived after the Syrian government, which occupied Lebanon's eastern highlands, permitted their transit to a base in the Bekaa valley.During the Lebanese Civil War, Hezbollah's 1985 manifesto listed its objectives as the expulsion of "the Americans, the French and their allies definitely from Lebanon, putting an end to any colonialist entity on our land", the submission of the Christian Phalangists to "just power", bringing them to justice "for the crimes they have perpetrated against Muslims and Christians", and permitting "all the sons of our people" to choose the form of government they want, while calling on them to "pick the option of Islamic government". Hezbollah organised volunteers who fought for the Army of the Republic of Bosnia and Herzegovina during the Bosnian War. From 1985 to 2000, Hezbollah participated in the South Lebanon conflict against the South Lebanon Army (SLA) and Israel Defense Forces (IDF), which finally led to the rout of the SLA and the retreat of the IDF from South Lebanon in 2000. Hezbollah and the IDF fought each other again in the 2006 Lebanon War.

Its military strength has grown so significantly since 2006 that its paramilitary wing is considered more powerful than the Lebanese Army. Hezbollah has been described as a "state within a state" and has grown into an organization with seats in the Lebanese government, a radio and a satellite TV station, social services and large-scale military deployment of fighters beyond Lebanon's borders. Hezbollah is part of Lebanon's March 8 Alliance, in opposition to the March 14 Alliance. It maintains strong support among Lebanese Shia Muslims, while Sunnis have disagreed with its agenda. Hezbollah also has support in some Christian areas of Lebanon. It receives military training, weapons, and financial support from Iran and political support from Syria.Since 1990, Hezbollah has participated in Lebanese politics, in a process which is described as the Lebanonisation of Hezbollah, and it later participated in the government of Lebanon and joined political alliances. After the 2006–08 Lebanese protests and clashes, a national unity government was formed in 2008, with Hezbollah and its opposition allies obtaining 11 of 30 cabinet seats, enough to give them veto power. In August 2008, Lebanon's new cabinet unanimously approved a draft policy statement that recognizes Hezbollah's existence as an armed organization and guarantees its right to "liberate or recover occupied lands" (such as the Shebaa Farms). Since 2012, Hezbollah involvement in the Syrian civil war has seen it join the Syrian government in its fight against the Syrian opposition, which Hezbollah has described as a Zionist plot and a "Wahhabi-Zionist conspiracy" to destroy its alliance with Bashar al-Assad against Israel. Between 2013 and 2015, the organisation deployed its militia in both Syria and Iraq to fight or train local militias to fight against the Islamic State. The group's legitimacy is considered to have been severely damaged due to the sectarian nature of the Syrian war. In the 2018 Lebanese general election, Hezbollah held 12 seats and its alliance won the election by gaining 70 out of 128 seats in the Parliament of Lebanon. Nasrallah declared on 2021 that the group has 100,000 fighters.Either the entire organization or only its military wing has been designated a terrorist organization by several countries, including by the European Union and, since 2017, also by most member states of the Arab League, with two exceptions – Lebanon, where Hezbollah is the most powerful political party, and Iraq. Russia does not view Hezbollah as a "terrorist organization" but as a "legitimate socio-political force".