Wife of Henry, Duke of Bavaria. They were both devout and he founded Bamburg Cathedral.
Being devout did not stop Henry from suspecting his wife of infidelity, and she was made to walk barefoot over fifteen red-hot plowshares to prove her innocence. Which she did — there was not so much as a tiny blister.
After his death she went to live an even more pious life in a monastery she had founded in Hesse.