The "Hidden Imam" refers to the twelfth Imam in Shia Islam, known as Imam Muhammad al-Mahdi. He is believed to have gone into occultation in the 9th century and is expected to return as a messianic figure to bring justice and peace to the world. His absence is a central belief in the Twelver branch of Shia Islam. Shia Muslims believe that the Hidden Imam is still alive but hidden from human sight. During his occultation, he is thought to guide the faithful through spiritual means. His return, known as the Mahdism, is anticipated to coincide with the end times, marking a significant event in Islamic eschatology.