I would like to propose that Felicia of Normandy, supposedly a daughter of Robert I, Duke of Normandy and half or full sister of William 'the Conqueror' is considered Disproven.
I've updated her profile to explain why I think she never existed and also that she may have originated in an 1870 publication as Felicia de Hastings, the daughter of a Robert de Hastings but also under that name there is no evidence that she ever existed.
I have already detached her as a daughter of Robert, Duke of Normandy, and have proposed that she be detached as the wife of Rognvald Brusesson.