(Bloomberg) -- With AT&T Inc. tightening control over its media operations, a real-life “Game of Thrones” is underway.

Richard Plepler, who helped create some of TV’s most memorable programs over three decades at HBO, said Thursday he plans to step down as CEO of the premium cable network. And David Levy, president of Turner Broadcasting, is expected to announce his departure on Friday, a person familiar with the matter said.

“Hard as it is to think about leaving the company I love, and the people I love in it, it is the right time for me to do so,” the 60-year-old Plepler said in a memo to staff.

The executive helped turn HBO into a jewel of the cable-TV industry. He oversaw hits such as “Game of Thrones’’ and “Silicon Valley’’ and shepherded the network’s push into online TV. But changes are afoot now that AT&T is the owner. The telecom giant acquired HBO as part of its $85 billion acquisition of Time Warner last year.

Just this week, AT&T beat back an attempt by the Justice Department to unwind the deal. That lifted a shadow over the merger, freeing the Dallas-based company to make more changes.

Levy is a major figure in the sports business world, having negotiated long-term broadcast rights deals with sports leagues such as the National Basketball Association, the NCAA men’s basketball tournament, the PGA of America and Major League Baseball.

‘The Match’

He helped create “The Match,” a head-to-head golf showdown between Tiger Woods and Phil Mickelson that aired across AT&T’s properties last fall. He’d also begun Turner’s foray into sports betting, inking a deal with Caesars Entertainment Corp. that made the casino operator the presenting sponsor of all gambling programming across Turner.

The Information website previously reported on Levy’s departure.

AT&T is expected to consolidate its TV networks into one division, which would deprive current executives of the autonomy they once enjoyed. As CEO of HBO, for instance, Plepler oversaw everything from production to legal to finance.

Plepler is a titan of the TV industry, a fixture on the New York media scene and political fundraiser. He took over HBO after serving as the head of communications to Jeff Bewkes, who rose from HBO to run all of Time Warner.

“We’ve created a great and unique enterprise,” Plepler said in the memo. “And I know that you will protect its legacy and do all to enhance its future in the years to come.”

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