Liwa Abu al-Fadl al-Abbas meaning Brigade of Abu al-Fadl al-Abbas, also known as the al-Abbas brigade is a mainly Shia Syrian militant group which operates throughout Syria. It is named after the nickname of Al-Abbas ibn Ali. The group rose in prominence in reaction to the desecration of various shrines, heritage sites and place of worship by rebels during the Syrian civil war and subsequently collaborated with the Syrian Army. Its role is largely defensive rather than offensive, largely in places of interest in Syria, such as the Sayyidah Ruqayya Mosque, Al-Nuqtah Mosque and Sayyidah Zaynab Mosque, Hujr ibn Adi Mosque, Umayyad Mosque, Great Mosque of Aleppo, Nabi Habeel Mosque, Bab al-Saghir, Uwais al-Qarni Mosque, Palmyra, Krak des Chevaliers, Ancient City of Bosra, and the surrounding areas. In May and June 2013, Reuters reported a split had developed between al-Abbas brigade forces over finances and leadership which erupted into a gunbattle. Many non-Syrian members subsequently formed a different brigade.
On 19 May 2014, fighters from the Nour al-Din al-Zanki Brigade claimed to have took over the al-Abbas Brigade's regional headquarters in Aleppo. As ISIS made significant gains in Iraq in mid 2014, the group was forced to return home to defend the faltering Shi'ite led government in Baghdad.