Jafar ibn Ali al-Hadi

Ja'far ibn Ali ibn Muḥammad al-Hadi ()( 226-271 A.H., c.840 AD - c.885 AD), also known as Ja’far al-Kadhab (the Liar), was the son of the tenth Shi'a Imam, Ali al-Hadi. He claimed to be an Imam and established his own sect of followers.
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.
Challenge.
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. 