In Islamic traditions, the promised Mahdi’s identity and personality who is one of the indisputable beliefs among all Islamic sects is clearly and precisely stated. He is a man of the Prophet’s progeny and the Household, with the same name as of the Prophet, Alavi, Fatemi and Hussayni, and “Hassan” is his father’s name. However, in some traditions, the promised Mahdi (A.S) is from the House of Abbas, the Prophet’s uncle, and from the descendant of Imam Hasan Mojtaba and his father’s name is “Abdollah”. Meanwhile, this paper investigates this group of traditions with a descriptive-analytic approach, it has found that these traditions cannot be invoked due to their incompatibility with authentic and frequent traditions and because of the weakness of their documentation. At the same time, some interpretations and justifications have been stated for them that assuming the validity of these justifications, these traditions are not incompatible with the other ones.