Dragon (animal)

Dragon: is an animal in the world of One Piece. It is a dragon, or a reptile of some sort, capable of flight.

Senneryu(Filler Species)
A Sennenryu or ''Thousand Year Dragon". They come from Warship Island's mostly submerged Dragons Nest.

They only appear in the anime only Warship Island Arc but are also referenced in the Ocean's Dream arc.

Wano Dragon(Canon Dragon)
However, Oda had recently mixed the Monsters story to the One Piece main story. Hogback remarked that Ryuuma has slain a Dragon in Wano Country.