I'm not discussing Franklin only because she was a good at x-rays, though in itself it's quite an achievement. Franklin had a great deal to do with the discovery of DNA structure, because she managed to take this picture:
What I do know was that this picture, one of the key elements leading to the discovery of DNA structure by Crick and Watson, was taken by Franklin's colleague and showed it, without her permission, to Crick and Watson.
They built their model based on this x-ray photograph, in addition to everything else they knew. Most think they couldn't have done it without Franklin's photo -- at least not so fast, which means they might not have been the first.
Now, not to remove the credit from Watson and Crick. They put together many pieces of a complex puzzle and came out with the right answer. That's an incredible achievement.
When they published their structure in 1953, however, the only mention of Franklin's work was as a footnote. Ten years later, Watson published a memoir recounting his discovery of DNA structure, The Double Helix. He discredited Rosalind Franklin on every occasion, calling her 'Rosy' and burying her contributions under allegations that she couldn't interpret her own data.
Crick, Watson and Wilkins received a Nobel Prize in 1962 for their work on DNA and other nucleid acids.
Franklin died in 1958, at 37, due to the consequence of x-ray exposure (turns out, x-rays are like radium in this regard).
The rules of Nobel Prizes forbid posthumous nominations. Her name isn't on it, and will never be.
Thankfully, her story is becoming more widely known, and she is increasingly frequently included in the tales behind the discovery of DNA structure, perhaps one of the biggest scientific discovery of our times.