from BBC News:
Piltdown Man went from being one of the biggest discoveries of the 20th Century to being its greatest scientific embarrassment.
On 21 November 1953, the fossils discovered 40 years earlier and acclaimed as the "missing link" between apes and humans were finally revealed to be forgeries.
Today, the word Piltdown is a term of abuse, used to label any fraudulent or shoddy research.
http://news.bbc.co.uk/1/shared/spl/hi/sci_nat/03/piltdown_man/html/default.stm
That one ranks right up there with Michael Bellisle and the recently-added Douglas Brinkley frauds.