Wylla is an unseen character mentioned in the first season, the alleged mother of Jon Snow. However, while she does exist, with the revelation that Jon's parents are Rhaegar Targaryen and Lyanna Stark, her role with regards to Jon is unknown.
"Wylla" is pronounced "Why-luh," not "Will-uh."
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.
Watching Jon training his men in the practice yard of Castle Black, Selyse Baratheon dismisses him, opining that he is just the bastard son of some tavern slut that Eddard encountered. Her husband Stannis Baratheon, however, says he doubts that. Having known Eddard personally, he says it really wasn't the way of the honorable Ned Stark to frequent prostitutes the way that Stannis's own brother King Robert did.
During Greensight, Bran Stark discovers that Jon is not Ned Stark's son at all - he is actually Lyanna Stark's son, fathered by Rhaegar Targaryen, her kidnapper, and born in the Tower of Joy while Ned and Howland Reed fought the last two Targaryen loyalists. This revelation does not debunk Wylla's existence, but she is certainly not Jon's mother.
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, Arya later learns Wylla is a servant of House Dayne of Starfall and has been for many years. When she is with the Brotherhood Without Banners, one of their members is the young Edric Dayne, the new head of House Dayne. He explains that Wylla was his wet-nurse at Starfall, and that she previously also nursed Jon (who is about four years older than Edric). He doesn't know how or in what circumstances Wylla met Eddard, because he was born a few years after Eddard and Jon left, and no one ever said more about it. Wylla was therefore alive for some time after Jon's birth, but it is unknown 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 - thus no one denies that Jon must have Stark blood in him.
Throughout the course of the novels, many characters mention rumors about other women who could be Jon's mother, or speculate about it themselves. Catelyn herself heard maidservants discussing the rumor that Jon's mother was Ashara Dayne of Starfall - Edric's own aunt, not just a servant. Ashara's brother was Arthur Dayne of the Kingsguard, whom Ned and his allies killed in the final confrontation of the war, the Showdown at the Red Mountains. Afterwards Ned returned the Dayne ancestral sword Dawn to Starfall out of respect, at which Ashara unexpectedly committed suicide by throwing herself off a cliff into the sea. The rumor was that Ashara didn't simply kill herself because her brother died in war (which happens to many women), but out of grief that her own lover had killed him. Catelyn asked Eddard about Ashara and Jon once early in their marriage: it was the only time Eddard ever truly became angry at her and frightened Catelyn. He said nothing, but commanded her never to ask about Ashara or about the identity of Jon's mother ever again, and indeed she never did afterwards. Even so this was only one of the more prominent of several rumors about the identity of Jon's mother. Others say that she was a fisherman's daughter in the Vale, where Eddard had been staying as a ward of Jon Arryn when the war broke out, and that he fathered Jon on her as he was fleeing back to the North to raise its armies after the Mad King killed his father and brother.
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 Eddard isn't in a position to refuse his king 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.
Following the revelation in the Season 6 finale of the TV series that Jon Snow's parents were actually Lyanna Stark and Rhaegar Targaryen, it is unclear what role Wylla played in the events surrounding his birth. However, Wylla is confirmed to be a real person, in service to House Dayne. After leaving the Tower of Joy with the infant Jon, Eddard did first travel to House Dayne's castle-seat at Starfall, to return their ancestral sword Dawn which he took from Arthur Dayne after he died in their skirmish. Edric Dayne adamantly insisted that Wylla was a wetnurse to the infant Jon: apparently, Ned hired Wylla as a wetnurse and stayed at Starfall for some time until the baby Jon was large and strong enough for the long journey to Winterfell - and when pressed for what Jon's mother's name was, Eddard simply gave the name of Jon's nurse, confident that her obscurity, low birth, and geographic distance from Winterfell and King's Landing would protect her from reprisal or investigation.
- ↑ 1.0 1.1 
- ↑ 2.0 2.1 The Winds of Winter
- ↑ 3.0 3.1 3.2 "The Kingsroad"
- ↑ "Baelor"
- ↑ "Sons of the Harpy"
- ↑ Tapper, Jake (March 28, 2013). Game of Thrones co-creator on gaining George R.R. Martin's trust CNN.
- ↑ http://www.westeros.org/Citadel/SSM/Entry/Many_Questions2
- ↑ Borgo, Érico (April 23, 2012). Omelete Entrevista Kit Harington e Richard Madden. Omelete.
|Title(s):||Lord of Starfall|
|Deceased members:||Dyanna Dayne · Beric Dayne · Arthur Dayne|