The Lady
The Goddess Who Must Not Be Named (also known as the million to one chance). She is constantly opposed to Fate, and she is just as difficult to understand, although where he is implacable, she is capricious. Since everyone believes in her, she does not need to be worshipped, and would regard such a thing as taking her for granted. Her favour instantly disappears if she believes someone is relying on her, or calls her by name (though it is stated in The Colour of Magic that she is attracted to the sound of dice). Attempts to worship her by some members of the Guild of Gamblers led to their deaths within a week - after all, being lucky doesn't necessarily mean having good luck.Her appearance is hard to determine. After witnessing her in person, Rincewind and Twoflower were not able to agree upon what she had looked like, other than that she "appeared to be beautiful" and had green eyes. Her eyes are her defining feature: no Discworld God can change the nature of their own eyes, and hers are green from edge to edge, without iris or pupil.
When playing games with mortals, The Lady never sacrifices a pawn, and doesn't play to win, but rather plays not to lose. Rincewind, who refuses to believe his continued survival against the odds is anything other than coincidence, is one of her favourites.
The Lady appears in The Colour of Magic, Interesting Times and The Last Hero