The belgian comic album "Le complice d'Iznogoud" has a nice and long one. A fay keeps appearing each time a particular swear word is used, she grants a wish to someone present and promptly vanish, to reappear the next time with one less piece of clothing.
I believe she starts wearing about 12 pieces, and it takes the whole album to get her naked. Unfortunately she's absolutely indiferent to the fact, so not really ENF.
Sorry, got no images.
This is also a favorite of mine, let's see if I can recall any other.
