ROMEO: I dreamt a dream tonight.
MERCUTIO: And so did I.
ROMEO: Well, what was yours?
MERCUTIO: That dreamers often lie.
ROMEO: In bed asleep while they do dream things true.
MERCUTIO: Oh, then, I see Queen Mab hath been with you.
BENVOLIO: Queen Mab, what’s she[?]
MERCUTIO: She is the fairies’ midwife, and she comes
In shape no bigger than an agate stone
On the forefinger of an alderman,
Drawn with a team of little atomi
Over men’s noses as they lie asleep.
Her wagon spokes made of long spinners’ legs,
The cover of the wings of grasshoppers,
Her traces of the smallest spider’s web, (Shakespeare, 1.4.50–62)

Queen Medb (or Queen Maeve, there's more than one alternative spelling) is the mythical queen of Connacht in the Ulster Cycle of Irish mythology. Cunning and ambitious, she was seen as a goddess of sovereignty that kings had to marry so they could have control of her land. She's also associated with mead, a drink offered to newly crowned kings, and her name was often interpreted as "she who intoxicates". She also frequently opposed the hero Cu Chulainn.

She was later popularized (under the name Queen Mab) by William Shakespeare, most notably being described in Romeo & Juliet (seen above).