Elizebeth Friedman
The codebreaker who took down rum-runners and Nazi spy rings, and whose work J. Edgar Hoover was happy to take credit for.
Elizebeth Smith, born in 1892, was hired by Riverbank in 1916 to hunt for Bacon's cipher in Shakespeare's texts. There she met William Friedman, and they married the following year. During Prohibition she worked for the US Coast Guard, decrypting thousands of radio messages between smugglers' ships — and then testifying in court about what they said, which sank several syndicates.
In the Second World War her unit led the effort against German agent networks in South America, some of whose traffic was encrypted on Enigma. The FBI presented the results as its own, and her part stayed classified for decades. She died in 1980. Jason Fagone's 2017 biography The Woman Who Smashed Codes is the main reason her name is now known outside the NSA.