[G8 Diplomat]

Sunnis believe the Mahdi will be born to parents named Abdullah and Amina, which were Muhammad’s parents’ names.

Twelver Shi’ites think the Mahdi is the 12th imam, that is the twelfth sucessor to Imam Ali (Muhammad’s cousin). His name is Muhammad al-Muntazar. There are other sects of Shi’ites who differ on which imam is the Mahdi (some say the fifth, some say the seventh)....

[Just mythoughts]

Sunnis believe the Mahdi will be born to parents named Abdullah and Amina, which were Muhammad’s parents’ names. Twelver Shi’ites think the Mahdi is the 12th imam, that is the twelfth sucessor to Imam Ali (Muhammad’s cousin). His name is Muhammad al-Muntazar. There are other sects of Shi’ites who differ on which imam is the Mahdi (some say the fifth, some say the seventh)....

Thank you for giving me this summation of what "Mahdi" means to different sects of this religion.