William Shakespeare

Two pairs of Athenian lovers flee into a forest to escape an arranged marriage - and walk straight into a fight between the king and queen of the fairies. Puck, tasked with fixing things with a love-potion flower, gets the wrong couple instead, and what follows is chaos: swapped affections, a group of amateur actors rehearsing the world's worst play, and a weaver accidentally given a donkey's head and the fairy queen's undivided devotion.
One of Shakespeare's most purely enjoyable comedies - layered, funny, and still the reason "the course of true love never did run smooth" gets quoted four centuries later.