The most obvious one, Resurrection by Melissandre

Image source:http://watchersonthewall.com/wp-content/uploads/2015/01/Carice-van-Houten-as-Melisandre_photo-Helen-Sloan_HBO.jpg We all saw the Red Priestess, Melisandre coming back to Castle Black to inform Jon and Ser Davos about Stannis' fall. If her purpose of coming back was only to convey the information then a raven would have sufficed. However, she sensed something special about Jon and in popular opinion, saw something to do with Snow or Jon in the flames when she looked for Azor Ahai. If Jon is really Azor Ahai then Melisandre would try to resurrect him. Remember Beric Dondarrion and Catelyn Stark (Lady Stoneheart according to the books) ? But this is too predictable and obvious and as we all know that this show is anything but predictable. However, she might try the ritual of the last kiss on him that brings back dead to life. But this in highly unlikely. Although, in order to bring Jon Snow as Azor Ahai back to life she might give up herself to the Lord of light.