He seems to be this one

"The Ushi-Oni (牛鬼, Ox Oni (demon)), or gyūki, is a yōkai from the folklore of western Japan.[1] The folklore describes more than one kind of ushi-oni, but the depiction of a bovine-headed monster occurs in most. Ushi-oni generally appear on beaches and attack people who walk there." https://en.wikipedia.org/wiki/Ushi-oni

So highly likely all the Elders are some mythological ancient gods and demons with their awakened fruits.