St. Pelagia

From Catholic Online - Saints & Angels - St. Pelagia:

Pelagia, more often called Margaret, on account of the magnificence of the pearls for which she had so often sold herself, was an actress of Antioch, equally celebrated for her beauty, her wealth and the disorder ofher life. During a synod at Antioch, she passed Bishop St. Nonnus of Edessa, who was struck with her beauty; the next day she went to hear him preach and was so moved by his sermon that she asked him to baptize her which he did. She gave her wealth to Nonnus to aid the poor and left Antioch dressed in men's clothing. She became a hermitess in a cave on Mount of Olivette in Jerusalem, where she lived in great austerity, performing penances and known as 'the beardless monk' until her sex was discovered at her death.