Wylla

"She must have been a rare wench to make Lord Eddard Stark forget his honor."

- Robert Baratheon to Eddard Stark.

Wylla is an unseen character mentioned in the first season. She's believed to be the mother of Jon Snow.

"Wylla" is pronounced "Why-luh," not "Will-uh."

Season 1
Over a meal, Robert Baratheon and Eddard Stark recall the names of several women they knew when they were younger. Robert recalls one woman whom he believes to be the mother of Eddard's bastard son Jon Snow, and Eddard confirms her name was "Wylla". The same as the first and only time they discuss it, Ned refuses to tell Robert what she looked like. Robert tells Eddard not to be too hard on himself as they were at war and could have died at any time.

Jon Snow says Ned Stark never told him who his mother was, or if his mother is still alive. Eddard had earlier promised Jon that he would talk to him about his mother the next time they met, although Eddard's subsequent beheading made that impossible.

Behind the scenes
The HBO Viewer's Guide for the TV series lists "Wylla" as Jon Snow's mother and deceased.

The question George R.R. Martin posed to David Benioff and D.B. Weiss at their first meeting to test their knowledge of the series was "Who do you think Jon Snow's mother is?" Beinoff guessed correctly.

Martin has stated the he does already know who Jon Snow's mother is and she will eventually be revealed. He has told some of the cast members secrets about their characters which have not been revealed in his novels yet however he has only revealed things which their characters would logically know already. Kit Harington has said that Martin therefore did not tell him who Jon Snow's mother is because his character does not know.

Harington says he prefers not to think too much about the various theories of his character's parentage as Jon Snow has come to accept that he will never learn the truth about his mother's identity.

In the books
In the A Song of Ice and Fire novels, Wylla is a servant of House Dayne of Starfall and has been for many years. She has been mentioned as being alive after Jon Snow's birth yet it is uncertain if she is still alive.

The novels make the mystery of Wylla truly being Jon Snow's mother more overt than in the TV series. Jon Snow is repeatedly noted for his striking physical resemblance to Ned at a young age, more so than any of Ned's trueborn sons.

Throughout the course of the novels, many characters mention rumors or speculate on other women as well as Wylla whom they believe to be Jon Snow's mother although. As in the TV series, the only woman that Ned himself ever identifies as Jon Snow's mother is "Wylla" - only once, when King Robert asked, and he wasn't in a position to refuse him an answer. Ned also tells King Robert that he does not want to discuss Wylla any further with him since his adultery was his dishonor towards himself and his wife.