HBOWhen people think about Game of Thrones, chances are they're thinking about the dragons. The later seasons of the HBO series were all about Daenerys Targaryen's three fire-breathing dragons, and the ongoing spinoff House of the Dragon has plenty of draconic action, too. Even when Dany wasn't going all "dracarys," late-era Game of Thrones was often about spectacle — the biggest battle or the biggest twist (not to mention the biggest budget and the most CGI).

That's not how Game of Thrones began, though. On a Sunday night 15 years ago, the most epic fantasy series announced itself with another genre: horror.The first episode of Game of Thrones, "Winter Is Coming," premiered on April 17, 2011, and it begins much the same way that the first book in George R.R. Martin's A Song of Ice and Fire series does.

It's a cold open (literally), as three members of what we'll later learn are the Night's Watch venture beyond the relative safety of the Wall. Will, the youngest, stumbles upon a grotesque arrangement of chopped-up icy body parts and the frozen corpse of a child pinned to a tree. He runs back to tell his superior officer, who dismisses his fear.

It's only when they return to the site that the White Walkers, blue eyed ghouls who we see only fleetingly, emerge to cut down Will's compatriots and command the dead to rise — including that little girl. The scene ends with Will surrounded as it slowly, ominously fades to black.As a standalone work of horror, this seven-minute opening is extremely effective. Will is our naive protagonist and his commander Waymar Royce is the snotty sort of horror victim viewers want to meet a gnarly end.

The pacing is deliberate and the dialogue is sparse. Instead, "Winter Is Coming" lets the images and Will's terror at what he's seeing largely speak for itself. Those images are indeed haunting.

One of the first visuals in HBO's big new series is the frozen body of a child, who rises from the dead minutes later with cold blue eyes. Game of Thrones was not playing around.Rather than begin this extremely knotty and complex fantasy tale with a voiceover explaining the history of Westeros like how Galadriel opens The Lord of the Rings, Game of Thrones dumps viewers right into a short horror film. We don't even get much in terms of explanation of what's happening, as terms like "wildlings" or "the Wall" don't get defined until later in the episode.

Instead, we are shown that there is a dark force that confident men with their swords are unfamiliar with and unprepared to deal with.The rest of "Winter Is Coming" is not like this opening scene — not much of the first season is, in fact. After the title sequence, the first episode catches up with a shellshocked Will, who fled south of the Wall after somehow surviving the White Walkers. Ned Stark doesn't heed his warnings about dead men up north; he executes him for deserting the Night's Watch.

Ned has more mundane things to worry about, like a conspiracy that one of Westeros' royal families is behind the demise of the Hand of the King. With the exception of this opening scene, most of the first episode of Game of Thrones is about setting up the pieces for the titular Game of Thrones. The Starks, Lannisters, Baratheons, and Targaryens are all focused on the same metal chair.Game of Thrones pointedly doesn't begin with this pointy throne, though.

It's these frozen undead, looming and lurking while the rest of Westeros is unaware or willfully ignorant, that the series is really about. There are large stretches of Game of Thrones, especially in the first several seasons, that all but forget about this opening scene. The supernatural ice zombies north of the Wall do come up again in the first season when a dead member of the Night's Watch rises and attacks the Lord Commander in Episode 8; the White Walkers themselves don't appear again until the final episode of the second season.

The White Walkers might be out of sight and out of mind for the soldiers and schemers vying for the Iron Throne, but because Game of Thrones began with a demonstration of how scary they are, the true stakes and the genre at the series' heart is well established.A White Walker makes his shadowy first appearance in the first episode of Game of Thrones. | HBOGame of Thrones would more openly return to horror off and on throughout its eight-season run, like with the zombie-like stone men in the ruins of Valyria or Ramsay Bolton, wouldn't be out of place in a Saw or Hostel film. Most often, though, true horror was reserved for the White Walkers.

Sam's encounter in the sophomore season finale or the "Hardhome" episode, which mixed high-octane action with terrifying undead dread, come to mind. Sadly, the opening Game of Thrones only underscores how underwhelming the ending of the show was. By the final couple of seasons, the horror of the White Walkers was no match for our protagonists' plot armor. Although there were more decaying zombies and imposing White Walkers than ever