Queen Mab is a fairy referred to in William Shakespeare's play Romeo and Juliet, in which the character Mercutio famously describes her as "the fairies' midwife", a miniature creature who rides her chariot over the bodies of sleeping humans during the nighttime, thus helping them "give birth" to their dreams. Later depictions in other poetry and literature and various guises in drama and cinema have typically portrayed her as the Queen of the Fairies.
Not who you're looking for? Others named Queen Mab: poem by Percy Bysshe Shelley · horse born in the 1730s