Wylla

Wylla is a character mentioned in Game of Thrones. It is unknown if she will appear in the series.

Wylla is a common girl whom Eddard Stark claims is the mother of his bastard son, Jon Snow. Aside from Robert Baratheon, it is not known how widely this claim has been made. Jon himself does not know the name of his mother, her whereabouts or if she is alive or dead.

In the books
In the Song of Ice and Fire novels, Eddard tells Robert that Wylla is the mother of Jon Snow. Wylla was a serving girl in the retinue of Lady Ashara Dayne of Starfall in Dorne whom Eddard met more than twenty years before the events of the series. Catelyn Stark heard a rumour in Winterfell that Ashara Dayne herself was Jon Snow's mother, a rumour Eddard refused to comment on at all.