Name and Birth
In Shi'a hadiths, the Twelfth Imam (a) is referred to by names such as Ahmad, and 'Abd Allah. However, among the Shi'as he is most famously referred to as al-Mahdi which is one of his titles.In different sources, supplications, and ziyaras, the Twelfth Imam of the Shi'as is characterized with different kunyas and titles, the best-known of which are: al-Mahdi (المَهدی, guided), Ṣāḥib al-Zamān (صاحب الزمان, the owner of the time), Muntaẓar (مُنتَظَر, expected), Baqīyyat Allāh (بَقیّة الله, what remains with Allah), Muntaqim (مُنتَقِم, avenger), Maw'ūd (مَوعود, promised), Khātam al-Awṣīyā' (خاتَم الأوصیاء, the last successor), Ghā'ib (غائب, hidden), Ma'mūl (مأمول, hoped), and Muḍṭarr (مُضطرّ, distressed). Another well-known title of Imam al-Zaman (a) is "Qa'im" (قائم, upriser or standing).The names and titles of the Twelfth Shiite Imam (a) are mentioned in Sunni sources as well. In these source, "al-Mahdi" is the mostly mentioned title. The title "Qa'im" is rarely found in Sunni sources.
Imam al-Zaman's (a) Mother: Narjis
Imam al-Zaman's (a) mother is referred to in different ways: Narjis, Susan, Saqil or Sayqal, Haditha, Hakima, Malika, Rayhana, and Khamt. In general, there are four accounts of her life and characteristics. According to a hadith cited by al-Shaykh al-Saduq in his Kamal al-din wa tamam al-ni'ma, Imam al-Zaman's (a) mother was a Roman princess. And in other hadiths, her life story is not mentioned and it is only said that she was trained and raised in the house of Hakima, the daughter of Imam al-Jawad (a). According to a third group of hadiths (cited by al-Mas'udi in his Ithbat al-wasiyya), Imam al-Zaman's (a) mother was not only raised in the house of Imam al-Hasan al-'Askari (a)'s paternal aunt, but was also born there. The last group of hadiths has a fundamental difference with these three groups. According to these hadiths, Imam al-Zaman's (a) mother was a black bondwoman. The first three groups of hadiths can be considered as complementary, but the last one cannot be reconciled with them. However, some scholars have tried to reconcile the last group of hadiths with others by taking it to be concerned with Imam al-Zaman's (a) nurse.
Time of Birth
Some old sources did not talk about the birth date of Imam al-Mahdi (a), taking it to be a secret. However, many Shiite and some Sunni hadiths take the year of the Twelfth Shiite Imam (a) to be 255/869 or 256/870.
There is also a disagreement about the month in which the Imam (a) was born. The majority of scholars take it to be Sha'ban as is evidenced by many old Shiite sources. However, some Shiite and Sunni sources take it to Ramadan, and some Sunni sources take it to be Rabi' I or Rabi' II. In historical sources, there are different accounts of the day on which the Twelfth Imam (a) was born, the best-known of which is Sha'ban 15th.
Place of Birth
Historians who talked about the issue agree that Imam al-Zaman (a) was born in the house of his father, Imam al-Hasan al-'Askari (a), in Samarra. The house is now part of the shrine of Imam al-Hadi (a) and Imam al-'Askari (a). Imam al-Hadi (a) and Imam al-'Askari (a) were summoned to Samarra, the center of the Abbasid Caliphate, years before the birth of Imam al-Zaman (a) and lived there until they were martyred.