The sleeping potion that makes you sleep like death and wake up safely. The statue scene in A Winter's Tales -- the oracle, of course, makes it fantasy, but what people remember is the fakery of the statue scene -- partly, no doubt, because of its mythic structure, the revival of spring. Whether Twelfth Night makes sense taking the characters at face value
For horror, of course, there's Titus Andronicus.
Some suggestions for other authors were thrown about. Alas, I remember only that I recommended A Midsummer's Tempest, and Prospero Lost, Prospero In Hell, and Prospero Regained.