James Watson and Francis Crick won the Nobel Prize for discovering the structure of DNA, but there was a catch.  These men discovered the structure of DNA based upon experiments performed by this person?

Rosalind Elsie Franklin was an English biophysicist and X-ray crystallographer who made important contributions to the understanding of the fine molecular structures of DNA, RNA, viruses, coal and graphite. Franklin is still best known for her work on the X-ray diffraction images of DNA. Her data, according to Francis Crick, were “the data we actually used” to formulate Crick and Watson's 1953 hypothesis regarding the structure of DNA. Furthermore, unpublished drafts of her papers (written as she was arranging to leave the unsupportive research situation at King's College London) show that she had indeed determined the overall B-form of the DNA helix. However, her work was published third, in the series of three DNA Nature articles, led by the paper of Watson and Crick which only vaguely acknowledged her evidence in support of their hypothesis.