 Another early instance of the name is "Gregge", recorded in 1306, within the "Feet of Fines" (for Essex); and as Greggez in 1504, within the "Register of the Freemen of the City of York".Gregg as a Scottish surname, a variant of the Scottish Clan MacGregor.Theodoxus danubialis

Theodoxus danubialis is a species of small freshwater snail with an operculum, an aquatic gastropod mollusk in the family Neritidae, the nerites.