The White Walkers love an art project, and the season premiere of the final stretch of Game of Thrones episodes only seeks to reaffirm that. In one of the last scenes of the episode, Tormund Giantsbane, Beric Dondarrion, Eddison Tollett, and friends, who somehow survived the Night King's attack on the Wall, are patrolling the Last Hearth and come across the latest creepy masterpiece from our undead friends. It's a small boy from the House of Umber, strung up and surrounded by severed human limbs, arranged in a familiar spiral pattern.
Earlier in the episode, we saw this child, Ned Umber, head of the decimated House Umber, being ordered by Sansa to bring his people to Winterfell as protection against the Night King's advancing army. Turns out that return journey to Last Hearth was ill-timed: It appears that the big bad -- last seen in the Season 7 finale burning down the Wall with his new ice dragon -- managed to intercept the boy. How? We're not exactly sure, but the upshot is that Ned's dead.
The moment allows for one of the most perfectly executed jump scares in series history, as the child's eyes open and his head turns behind our friends as they plot out their next move. But there's also probably greater significance to the symbol our undead friends left behind. The spiral and related shapes have continually popped up in iconography related to the White Walkers.