Antonius (Ancient Greek: Ἀντώνιος) was a physician of ancient Greece. He was mentioned by the medical writer Galen, and referred to as "the herbalist" (ὁ ῥιζοτόμος). He must have lived in or before the second century. The medical formulae of Antonius are several times quoted by Galen, and he is perhaps the same person who is called " the druggist" elsewhere (φαρμακοπώλης). Possibly they may both be identical with Antonius Castor, but of this there is no proof whatever. He is possibly the same man as Antonius Castor, the renowned botanist and pharmacologist mentioned Pliny the Elder.