HOLLYWOOD — HBO was already preparing for a challenging life after the end of "The Sopranos." Now, it's grappling with the void created by the ouster of the man who introduced America to some of the most provocative and sophisticated shows on television.

The downfall of Chris Albrecht has rocked HBO, where, until his firing last week, he had served as chief executive for nearly five years. Many top managers in the tightly knit organization have worked together for decades — Albrecht had been there since 1985 — molding the premium cable network into a defining force in popular culture and a jewel in the Time Warner Inc. empire.

"He has his fingerprints on nearly everything we've done," said Colin Callender, president of HBO Films. "Chris was a great manager and he had enormous respect for his executives and empowered them all to do good work."

Industry experts and insiders called Albrecht a visionary, the force behind HBO's move into original programming.

They said Albrecht's imprint on the TV business could be as lasting as those made by other celebrated creative forces, including former NBC executives Grant Tinker and the late Brandon Tartikoff.

Albrecht's ruin also will leave a mark: HBO dumped him after his weekend arrest in Las Vegas on suspicion of assaulting his girlfriend and the recent revelation that the cable network had paid a cash settlement to a female subordinate who alleged that Albrecht had shoved and choked her at the cable channel's Los Angeles office in 1991.

But even with all the shock and sadness at HBO, analysts said Albrecht wasn't indispensable.

"This is an unfortunate circumstance, and it will likely have a slight negative impact on the company," said Deana Myers, an analyst with research firm SNL Kagan. "But they have a lot of talented people. HBO won't be going out of business."

The interest in who will succeed Albrecht may be less intense than in what will happen after "The Sopranos." Candidates include Chief Operating Officer Bill Nelson; Eric Kessler, president of sales and marketing; and Richard Plepler, communications chief, people close to HBO said. Nelson has taken over Albrecht's duties for now.

Although shows such as "Entourage," "Big Love," "The Wire" and "Rome" have attracted legions of fans, HBO has failed to develop a broad-based hit since "Six Feet Under," which ran from 2001 to 2005.

Landing another mega-hit will be "an enormous challenge," said Brad Adgate, research director for Horizon Media. "They've set a standard that's almost impossible to beat."

Unlike most TV networks and cable channels, HBO isn't dependent on advertising revenue tied to the ratings of its shows. Instead, about 80 percent of revenue comes from subscriber fees. HBO is the most profitable of all the cable channels in terms of cash flow, Myers said. Last year, its net income was $1.2 billion on $3.4 billion in revenue.

HBO executives said the loss of "The Sopranos" wouldn't necessarily lead to an exodus in subscribers. They didn't flee during the two years when "The Sopranos" was on hiatus and after "Sex and the City" had ended its run in 2004.

Plus, HBO has been preparing for the loss of "The Sopranos" for more than two years.