The curtain came down on an era for HBO Wednesday night as it hosted a massive final season premiere event for “Game of Thrones.”

The screening of the first of the show’s last six episodes was a spectacle unto itself. Radio City Music Hall was packed with industryites and celebrities who are far removed from the Seven Kingdoms. The after-party at Ziegfeld Ballroom was decked out with all manner of fiery motifs evoking the show’s blend of barbarism, beauty and warrior spirits.

The mood among many in the small army of HBO and WarnerMedia executives on hand for the “Thrones” sendoff was as anxious as those who are in the hunt for the Iron Throne. The beginning of the end of “Thrones” has coincided with a major shakeup in the management of HBO under its new parent company AT&T.

“I don’t know if I’m OK,” said a longtime HBO executive who was asked that question more than once by guests on Wednesday. “Ask me in a few months.”

Compounding the unsettled feeling for many employees is the fact that HBO’s New York headquarters will relocate in a few weeks from its longtime home in Bryant Park to WarnerMedia’s new digs in Manhattan’s Hudson Yards. For the first time in years, HBO will be housed within in the corporate offices of its parent company rather than in a separate outpost. It’s a prudent financial move but one that symbolizes a loss of autonomy.

The flood of praise that flowed from those who spoke on stage at Radio City reinforced the rich legacy of the previous regime, which ended when Richard Plepler resigned Feb. 28 as chairman-CEO after 27 years with the brand. Five days later, NBC and Showtime alum Bob Greenblatt was named chairman of WarnerMedia Entertainment, overseeing HBO, TNT, TBS and WarnerMedia’s nascent streaming service.

Plepler was hailed as a warrior in his own right for backing “Game of Thrones” in its infancy when it was wildly expensive and a major tonal departure from the shows that had clicked for HBO in the past. Not only did Plepler “greenlight the most expensive pilot in the history of HBO,” HBO programming president Casey Bloys observed, “he greenlit the most expensive pilot re-shoots in the history of HBO.”

“Thrones” showrunners David Benioff and D.B. Weiss were effusive in crediting Plepler for providing them with such staunch support, despite their lack of experience in TV when the show began in 2011.

“We don’t know why you said yes,” Benioff said. “We are all here because of the choice you made.”

Before the screening, Plepler was feted by a line of well-wishers that snaked down the aisle in the orchestra section. Plepler told Variety that “Thrones” qualified as a “once-in-a-generation kind of show” and said he was happy to see the cast and crew enjoying a “triumphant” celebration of their work.

“Even as the show became more and more successful and they all became more and more famous, what remained was their grace and humility in addition to their talent, and that’s the rarest of things,” he said. “They were just a privilege to work with. It’s an honor for me to be here today to celebrate them.”

The end-of-an-era vibe at the gathering was also underscored by “Thrones’ ” status as a TV unicorn – a culture-changing, mammoth hit that offers an increasingly rare opportunity for tens of millions of fans to enjoy a shared experience. The storytelling is so urgent and the visuals are so stunning that it even transcends the flexibility that viewers now prize thanks to the on-demand revolution.

“I watch ‘Veep.’ I watch ‘Billions.’ I watch ‘Barry,’ ‘The Good Fight,’ ‘Better Call Saul.’ But I watch them when it’s convenient for me,” said CNN anchor Jake Tapper, who attended the screening and after-party. “ ‘Game of Thrones’ may be the last show where it’s like — OK, it’s time. Everybody go to bed, Daddy’s watching ‘Game of Thrones.’ ”

Tapper was not disappointed by the season premiere episode, calling it “unbelievable television.”

“Thrones” fans bracing for the heartbreak of bidding farewell to Daenerys, her dragons and the rest of the gang will have to absorb the blunt lesson delivered toward the end of the Season 8 premiere episode by a key supporting character. The same is true for House HBO.

“Nothing lasts,” the character says as he urges his companion to face up to “an unpleasant truth.”

(Pictured: HBO’s Casey Bloys with “Game of Thrones” star Emilia Clarke, showrunners David Benioff and D.B. Weiss and “Thrones” star Peter Dinklage)

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