Dhu'ayb ibn Musa al-Wadi'i al-Hamdani (Also Zoeb, Zoaib & Zuayb; Arabic: ذؤيب بن موسى الوادعي الهمداني, romanized: Dhuʾayb ibn Mūsā al-Wādiʿī al-Hamdānī; died 29 April 1151) was the first dāʿī al-muṭlaq, a position of spiritual authority in Tayyibi Isma'ili Islam.

Dhu'ayb began his career as a member of the pro-Fatimid, Musta'li daʿwa in Yemen, and rose to become an assistant of the local chief missionary (dāʿī), Yahya ibn Lamak.

In Yemen, the hitherto pro-Fatimid queen Arwa sided with the Tayyibis and broke off relations with Cairo, while the regional dynasties of the Hamdanids and the Zurayids recognized al-Hafiz's claims.

Nevertheless, precisely due to the establishment of an independent hierarchy, separate from both the Fatimids and the Sulayhids, the Tayyibi daʿwa managed to not only survive both regimes, but also spread in the region.

A skilled warrior and notable poet and theologian, al-Khattab became Dhu'ayb's principal aide, and an important asset to the Sulayhid and Tayyibi cause, until his murder by his nephews in a dispute over control of al-Hajur in 1138.