- This article is about the dispute over the historical person named Kaysan. For the companion of al-Mukhtar al-Thaqafi, see Abu 'Amra Kaysan.
Different people were called Kaysan:
- Kaysan was the slave of Imam Ali (a) and he was martyred in the Battle of Siffin (37/657).
- Kaysan was the title or name of al-Mukhtar b. Abi 'Ubayd al-Thaqafi and Kaysanites are attributed to him. According to a narration, when al-Mukhtar was born, his father took him to Ali b. Abi Talib (a), Imam (a) cuddled him and call him "Kayyis" (in Arabic means cunning) and he was called Kayyis then. Some believe Kaysan was the title of al-Mukhtar al-Thaqafi which was taken after the name of one his companion known as Abu 'Amra Kaysan.. Also some stated that when Muhammad b. al-Hanafiyya sent al-Mukhtar to avenge blood of Imam al-Husayn (a) to Iraq, he found him cunning and clever, then he called him Kaysan.
- Kaysan (his kunya Abu 'Amra) was a man different from al-Mukhtar al-Thaqafi and based on some sources he was Abu 'Amra Sa'ib b. Malik al-As'adi (d. 67/686). Kaysanites are attributed to him, not to al-Mukhtar al-Thaqafi. He played a role in the Uprising of al-Mukhtar against Banu Umayya. He was a Mawali (freed slave) of Banu 'Urayna who were related to Bajila, the Arab tribe. It seems, as the mentioned Kaysan was not famous, those who attributed Kaysanites to him thought Kaysan was the title of al-Mukhtar al-Thaqafi.
- Some religious scholars believed the mentioned Kaysan was an unknown and fake person just like 'Abd Allah b. Saba'.
- The material for this article is mainly taken from کیسان in Farsi WikiShia.