The surname Al-Zaidi (Az-Zaidi) can denote one or both of the following:

• Sayyid Arab descendants of Zayd ibn Ali that either stayed in Kufa, Iraq or returned to Al-Hijaz.
• The use of the surname Al-Zaidi to designate association may be with the Zaidiyyah madhhab, whose adherents are found in Yemen. This is akin to the use of the surnames Al-Hanafi, Al-Maliki, Al-Shafi'i, etc.

People with the surname Zaidi trace their origins to the Islamic Holy City of Mecca, located in present-day Saudi Arabia. Zaid ibn Ali was the son of Ali ibn al-Husayn Zayn al-'Abidin who was the great grandson of the Islamic prophet Muhammad thus the descendants of Zaid ibn Ali are known as Sayyid- an honorific title bestowed upon to the descendants of Muhammad. In Present times, the Descendants of Zaid ibn Ali can be found in Iraq, Iran, Afghanistan, India and Pakistan. The ones in India and Pakistan carry the surname Zaidi along with Wasti (denoting Zayd ibn Ali's descendants from Wasit) with Sadaat-e-Bara and Sadaat-e-Bilgram as prominent communities, they are followers of Twelver Shi'ism not Zaydism which is largely restricted to Yemen.