MAYV
The warrior-queen of Connacht whose jealousy over a prize bull sets the entire Táin Bó Cúailnge in motion.
Medb ("she who intoxicates") rules Connacht from Cruachan, and insists on equal wealth with her husband Ailill down to the last animal — a boast that unravels when it turns out Ailill owns one bull, Finnbennach, with no equal in her own herds. Learning of an even greater bull, Donn Cúailnge, kept in Ulster, she raises an army to take it by force, and that campaign is the Táin Bó Cúailnge itself.
She is no distant instigator: Medb personally leads the invasion, negotiates single combats, and orchestrates the sorcery and broken taboos that eventually bring down Cú Chulainn, who alone holds Ulster's border against her while the rest of Ulster's warriors lie incapacitated under a curse. Medb survives the Táin's failure and appears in later tales as well, one of Irish mythology's most consistently formidable figures rather than a one-story villain.