Taqi Muhammad

Muhammad at-Taqi (True name: Aḥmad ibn ʿAbd Allāh ibn Muḥammad ibn Ismāʿīl (أحمد بن عبد اللّه بن محمد بن إسماعيل) or Aḥmad ibn ʿAbd Allāh ibn Muḥammad at-Taqi) (born AH 198 (813/814), died AH 225 (839/840), Salamia, Syria, Imam: AH 212 (827/828)-AH 225 (839/840)) is the ninth Ismāʿīlī Imam . As the Imam, he was the supreme spiritual leader of the Ismāʿīlī community from his appointment until his death. The Nizari and Mustaali trace their Imamate lines from him and his descendants who founded the Fatimid Empire. He was succeeded by his son, Ḥusayn ibn Aḥmad /Raḍī ʿAbd Allāh.

The 8th to 10th Ismāʿīlī Imams were hidden from the public, because of threats from the Abbasid caliphate, and were known by their nicknames. However, the Dawoodi Bohra in their religious text, Taqqarub, claim to have the true names of all 21 imams in sequence including those "hidden" imams: 8th Imam Abdillah-ibne-Mohammad the true name/ (Wafi Ahmad), 9th Imam "Ahmed-ibne-Abdillah (Taqi Muhammad), and the 10th Imam Husain-ibne-Ahmed(Raḍī ʿAbd Allāh).

Time line indicating Imam amongst other Shia Imam:

...
Wikipedia