Ad-Da'i Ahmad bin Ali al-Fathi (died 1349) was a claimant to the Zaidi state in Yemen, who posed as imam in 1329–1349, in rivalry with other figures.
Ad-Da'i (Missionary) Ahmad bin Ali al-Fathi was a seventh-generation descendant of Imam Abu'l-Fath an-Nasir ad-Dailami (d.
Ahmad bin Ali al-Fathi made his da'wa (call for the imamate) in 1329, from his base in the Sufian area.
However, he had to contend with three other claimants called al-Mu'ayyad Yahya (d. 1346), an-Nasir Ali bin Salah (d. 1329), and al-Wathiq al-Mutahhar (d. 1379–80).
Al-Mu'ayyad Yahya soon triumphed, and stood out as the main political force in the Zaidi territory until his death in 1346.