In Final Fantasy VII, there are three Bahamut summons: Bahamut, Neo Bahamut, and Bahamut ZERO.
The trio represents a progression of increasingly powerful versions of the series' signature dragon summon. The standard Bahamut is the first form encountered, while Neo Bahamut is a more advanced summon with a stronger presentation and attack. Bahamut ZERO is the rarest and most powerful of the three in the original game.
They are separate summon Materia rather than three names for one spell. Bahamut is obtained through the game’s normal exploration, Neo Bahamut is found later, and Bahamut ZERO is tied to the huge Materia side quest. The final summon’s Mega Flare attack is especially memorable because it launches its assault from space.
A frequent mistake is counting only the base Bahamut, or treating every appearance of the creature across the wider Final Fantasy franchise as part of Final Fantasy VII. The answer is three within the original Final Fantasy VII summon system; later games and spin-offs use additional Bahamut variants.