​Once it airs the eighth and final season of Game of Thrones, ​HBO will be temporarily left without a real signature show. Sure, it has some big series like Westworld, Barry, and Last Week Tonight With John Oliver, but Game of Thrones has been its major tent pole for the better part of a decade and losing it will be a big hit for the cable network.

It's currently making a prequel series to the show, but until that starts airing, HBO is subtly shifting its attention to the Watchmen series the network has been planning for some time. Based on the legendary graphic novel by Alan Moore of the same name, HBO recently created an Instagram account for the show and posted the first image from the production.

Who Watches The Watchmen? #WatchmenHBO

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Captioned with the quote "​Who Watches the Watchmen?," the short, soundless video has sent the internet into a fury trying to decipher who it depicts. The most popular theories are that it is either Rorschach, the masked protagonist of the original comic, or the Comedian, the jingoistic and militant hero whose death is the driving mystery behind the graphic novel.

While neither Rorschach or the Comedian are police officers and neither wears a yellow mask, Rorschach's famously morphing mask is similar in style and the yellow color evokes imagery of the Comedian's iconic smiley face pin. Though the show shares a name and is based on Moore's graphic novel, showrunner ​Damon Lindelof has revealed that his series will take place in an alternate timeline that loosely follows the events of the story.

While not much is known about the details of the series, the announced cast list includes the likes of Regina King, Jeremy Irons, Don Johnson, Tim Blake Nelson, Louis Gossett Jr., Yahya Abdul-Mateen II, Andrew Howard, Tom Mison, Frances Fisher, Jacob Ming-Trent, Sara Vickers, and Dylan Schombing.