The armies are gathering in Game of Thrones season 8 ahead of the Great Battle of Winterfell, but one character currently missing from the action is Red Priestess Melisandre. With so many major characters having been killed off over the last seven seasons, the absence of one of the survivors is conspicuous - but though she's not currently in Westeros, Melisandre is sure to return before the show ends.
Melisandre was mentioned in last week's episode, "A Knight of the Seven Kingdoms," when Arya quizzed Gendry on the strange night he had spent with the Red Woman. Back in season 3, Melisandre used Gendry's "king's blood" for a ritual in which Stannis prayed for the deaths of Balon Greyjoy, Robb Stark, and Joffrey Baratheon - all of which eventually came to pass. Stannis and Melisandre intended to then use Gendry as a human sacrifice, but fortunately Davos helped him to escape. Later, Melisandre was instrumental in bringing Jon Snow back to life, and then uniting him with Daenerys Targaryen.
We last saw Melisandre in Game of Thrones season 7, episode 3, "The Queen's Justice," where she told Varys, "I've done my part. I've brought ice and fire together" - referring to the meeting between Jon and Daenerys. Explaining that her presence would be a distraction if she stayed, and that she would be heading back to Volantis. When Varys advised her to stay there, she replied, "I will return, dear spider. One more time. I have to die in this strange country. Just like you." As further confirmation that Melisandre will return in season 8 - apparently to meet her death - one of the character posters for the final season showed her sitting on the Iron Throne:
The big question, then, is when Melisandre will return. Since she believes that she would be a distraction for Jon, and that her part in actually influencing the actions of kings is over, it seems likely that the Red Woman will stay away for a while longer - perhaps until the season finale. Her declaration that she will die in Westeros is a strong indication that she won't survive to the end of the show, so it's possible that she will be killed for the many atrocities she has committed over the last few years.
It's also possible that Melisandre will die a natural death, though such a thing is rare in Game of Thrones. As revealed when she removed her necklace, her youthful appearance is just a facade and she's actually a very old woman. Like Beric Dondarrion, she seems to only be alive because the Lord of Light wills it. If the fire god were to withdraw his favor, or decide that she had served her purpose, Melisandre's magic may run out and her age may finally catch up with her.