Dionysius Scytobrachion was a Greek grammarian and mythographer from Mytilene on Lesbos, active in the 3rd century BCE. He is known primarily through later testimonia, especially in the works of Diodorus Siculus, who cites him extensively for Argonautic and Libyan myths. His epithet "Scytobrachion," meaning "Leather-Arm," is of uncertain origin but may refer to a physical characteristic or a scribe’s protective sleeve.

Dionysius is credited with several prose works of mythological compilation. His Argonautica was a prose account used by Diodorus Siculus as a major source. His Libyan Stories concerned North African myths involving the Amazons and Athena, while his Dionysiaca treated myths of Dionysus. All three works are lost and survive only in fragments or citations.

Dionysius represents a significant figure in Hellenistic mythography. His works were comprehensive prose re-narrations that sought to provide coherent, sometimes rationalized versions of mythical cycles. His influence is most visible in Diodorus Siculus, through whom his mythological versions were transmitted to later antiquity.