Ashara Dayne

From Asoiaf

Ashara of House Dayne was the sister of Ser Arthur Dayne of the Kingsguard. Eddard Stark killed Ser Arthur in single combat and brought his sword back to Ashara, who was waiting in the castle Starfall on the shores of the Summer Sea.

Later rumours at Winterfell said Lady Ashara Dayne was the mother of Eddard's bastard son Jon Snow. When Lady Catelyn confronted Eddard about these rumours he told her never to ask about Jon again and put an end to the whispers about Ashara Dayne.