Kata'ib Sayyid al-Shuhada

The Master of Martyrs Battalions, or Kata'ib Sayyid al-Shuhada' (KSS; كتائب سيد الشهداء, The Battalions of the Master of Martyrs), officially the 14th Brigade, is a radical Iraqi Shia militia formed in 2013. Its stated mission is to protect "(Shia) shrines across the globe", preserve "Iraqi unity" and to "put an end to the sectarian conflict". KSS is funded, trained and equipped by IRGC's Quds Force and Hezbollah.

The group has been described as an Iranian proxy, and is one of the original militias that formed the Popular Mobilization Forces in 2014. The group has close ties to Badr Organization and Islamic Revolutionary Guard Corps.

KSS is also active in Syria, where its main focus is the protection of the Sayyidah Zaynab Mosque in a southern suburb of Damascus. It militarily supports the al-Assad Government in the Syria Civil War, and engaged in the Battle of Al-Shaykh Maskin in December 2014 in Syria in support of the Syrian army.

On November 17, 2023, KSS and its leader Hashim Finyan Rahim al-Saraji (also known as Abu Ala al-Walai) were declared Specially Designated Global Terrorists (SDGT) under the counterterrorism authority Executive Order 13224 by the United States. Additionally, al-Saraji was placed on Office of Foreign Assets Control's Specially Designated Nationals (SDN) List.