Alan Turing most certainly has been an unsung hero. That has been historically true of many, if not most, LGBT people who have done exceptional things, but did not hide their sexuality. Bayard Rustin is a great example. He is considered by many of his contemporaries, as well as historians to be the architect of the Black Civil Rights Era. Yet, for many years, his name all but disappeared in the Civil Rights story. Only in the past decade or so has he been given his due.
