There are repeated Traditions in the Sunni and Shi’ite books in our hands today which speak about caliphate of the twelve imams and caliphs after the Holy Prophet. These can be found in many of the famous Traditions of the Sunnis, like Sahih Bukhari, Sahih Tarmadi, Muslim Sahih Abu Dawoud and Musnad Ahmad. The question remains however, that: Who are these twelve Imams?