Flavius Hannibalianus (also Hanniballianus; died September 337) was a member of the Constantinian dynasty, which ruled over the Roman Empire in the 4th century.
Hannibalianus was the son of Flavius Dalmatius, and thus nephew of Constantine I. Hannibalianus and his brother Dalmatius were educated at Tolosa by rhetor Exuperius.
In 320s, Constantine called Flavius Dalmatius and his sons to Constantinople. Hannibalianus married Constantine's elder daughter, Constantina, in 335, and was made nobilissimus.
In occasion of the campaign of Constantine against the Sassanids (337), Hannibalianus was made Rex Regum et Ponticarum Gentium, "King of the Kings and of the Pontic People". Probably it was Constantine's intention to put Hannibalianus on the Pontic throne, after the defeat of the Persians.
The Persian campaign did not take place, because Constantine died in May 337. Hannibalianus died, as did his brother, in the purge of the imperial family that followed.