It IS possible to stay true to the decades of comics that built the mythos and character of the Joker (a manical demented madman) without stripping him of his basic tenents, being:
a PERMANENT physical appearance of a clownish nature (ie white skin, red lips, green hair), and a terrifying exhuberant LAUGH.
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It IS possible for the character of the Joker to maintain a sence of murderous insanity while keeping his traditional madcap persona. Here are two examples:
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