Joan the Wad is a mythological character in Cornish folklore. Specifically, she is Queen of the pixies (or piskeys), a race of tiny creatures usually associated with the area of Cornwall and Devon. Wad is a dialect word for torch.

Not much has been written on Joan, as the folklore of Cornwall relied on oral tradition for hundreds of years. She has been associated with Jack o' the Lantern, a will-o'-the-wisp type character who leads travellers astray on lonely moors, hence the rhyme:

Jack o' the lantern! Joan the wad,
Who tickled the maid and made her mad
Light me home, the weather's bad.

However, Joan is also thought to be lucky, and another rhyme runs:

Good fortune will nod, if you carry upon you Joan the Wad

Even today people will carry small figures of her for good luck, a small collection of which are housed at the Museum of Witchcraft in Boscastle.