Jon Snow’s real name was revealed in the Game of Thrones season finale, it seems

All you need is extra-strength hearing, the help of a lip-reading expert or to watch the scene about 50 times.

Jon Snow's parentage has been a talking point amongst fans of Game of Thrones for a long time now, and the season six finale confirmed that he is indeed the son of Lyanna Stark (sister of Ned Stark) and Rhaegar Targaryen (brother of Daenerys). One reddit user and Game of Thrones obsessive by the name of sparkledavisjr has watched the scene on repeat before coming to the conclusion that the words spoken softly by Lyanna Stark as she died were "His name is Jaehaerys." Jaehaerys is a name that will be familiar to those who know their Westerosi history. Jaehaerys was the name of the fourth Targaryen to sit the Iron Throne, known to have been wise and dignified. Jaehaerys was also the father of the Mad King Aerys Targaryen, and the grandfather of Rhaegar, Daenerys and Viserys. This image, uploaded to the official Making Game of Thrones blog confirms that Lyanna is indeed Jon's parent, as opposed to Ned Stark - as the show suggested at its outset.