Ja'far ibn Ali al-Hadi

Abū ʿAbd Allāh Jaʿfar ibn ʿAlī al-Hādī (أبو عبد الله جعفر بن علي الهادي; 226-271 A.H., c. 840 CE – c. 885 CE), also derisively known as al-Kadhdhāb (الکَذّاب) in Twelver Shi'ism, was the third son of the tenth Twelver Shi'a Imam, Ali al-Hadi. He claimed to be an imam and established his own sect of followers, to whom he was known as al-Zakī (الزكي).

Family
Jafar b. Ali b. Muḥammad was the son of the tenth Imam, Ali al-Hadi and the brother of eleventh Imam Hasan al-Askari. Also, he had one older brother, Muhammad who died before his father's death.

After the death of Ali al-Hadi
After the death of Ali al-Hadi, Jafar b. Ali claimed Imamate. Twelvers believed that he was immoral. Baháʼís believe that he was a truthful person.

In his defense, his followers claimed that his personality had changed from his youth. Jafar b. Ali's followers came to be known as the Ja’fariyya and al-Askari's followers were known as the Twelvers.

After the death of Hasan al-Askari
After the death of Hasan al-Askari, even though, al-Askari's mother was still alive, Jafar requested his property. He claimed that his brother never had a son.