Has there been a female knight?
Yes. There have been a few recorded female knights throughout history.
One was Joan of Arc, a French peasant girl and Catholic religious leader who claimed to receive visions from God telling her that she would liberate France from its English occupiers. Besieged by the armies of England and Burgundy, she led the French defense yet her armies were successful in liberating some territories such as Normandy after which it became more difficult for them to make any significant progress. The Siege of Orleans is seemingly her most important battle whereupon she convinced many French men-at-arms during the battle through words, example and deeds to join their gender opposite forces together until all alive were persuaded including Jacques d’Arc , her father