Goewin is a character in Welsh mythology, playing a pivotal albeit brief role in the tale of Math fab Mathonwy, one of the Four Branches of the Mabinogi.

In the narrative, the central figure Math fab Mathonwy faces a dire fate: he will perish unless his feet are continuously held in the lap of a virgin or he is engaged in warfare. Goewin fulfills this crucial duty until Math is deceived into going to war by his nephews Gwydion and Gilfaethwy. The nephews proceed to assault Goewin, violating her. Upon Math’s return, Goewin exposes the crime, leading Math to punish the two offenders by transforming them into various animals. Subsequently, Math weds Goewin, granting her authority over his realm as a means of restitution.