In Irish mythology Medb Lethderg ([mɛðv l͈ʲeθ.ðerɡ]; "red-side") was a goddess of sovereignty associated with Tara. She was the wife or lover of nine successive kings, including Fedlimid Rechtmar, Art mac Cuinn and Cormac mac Airt.
She is probably identical with or the inspiration for Medb of the Connachta in the Ulster Cycle (Byrne 2001).
The poem "Macc Moga Corbb celas clú" in the Book of Leinster is ascribed to her.
