Just the most satanic looking in a FF game, but just according to christianity. FF is fond of creatures based on demons and mythological beings.
Shiva, Bahamut, Glasyo Labolas, Diablo, Brothers, Edea, Chaos... just a few examples.
well stuff like Shiva are basically inspired by gods from their respective religions. then stuff like Bahamut and Leviathan have places in mythology. and beings like Chaos even though they look like a demon are never actually referred like this in ff games.
We live to make the impossible possible! -Lightning-
Not only Beelzebub, but Lucifer and Satan are also enemies in the FF series. As are other classic names that have been used for the devil over the ages, such as Belphegor, Mammon, Asmodeus, Astaroth, etc, etc.
In terms of demonology, the 72 demons of Solomon are an extremely common go-to reference for many, many enemies in the series. Check out the list and seem how many FF monster names you recognize there: