Lauer had served as co-host of the popular morning program Today for more than two decades, during which time he won over millions of early-to-rise TV viewers. But Lauer also earned criticism for his interviews as well as for his reportedly contentious relationships with women, both on-air and behind the scenes at Today.

With Lauer as the face of NBC’s cash-cow morning program, Today has been a ratings giant for years, even amid the show’s more recent battle with ABC’s Good Morning America for sunrise supremacy on weekday mornings. (While GMA often brings in more total viewers, Today lately has been more popular with the coveted younger demographics, winning the ratings battle in that key group for nearly 100 consecutive weeks.)

NBC News chairman Andrew Lack said in a memo to employees that the complaint against Lauer was the first of its kind during the anchor’s long tenure at NBC News, but it “represented, after serious review, a clear violation of our company’s standards.” Lack also added that “we were also presented with reason to believe this may not have been an isolated incident.”

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As Fortune already noted, Lauer has been one of NBC’s biggest names (and faces) for decades—and he had the salary to prove it, reportedly pulling in at least $20 million per year. Lauer’s importance to NBC matched the size of this huge paycheck, and his departure leaves huge shoes for someone to fill.

Lauer’s Today co-hosts Hoda Kotb and Savannah Guthrie made the tearful announcement of Lauer’s firing this morning (similar to what Charlie Rose’s female co-hosts did on CBS recently) leading to some speculation that the two women could be in line for new roles on Today in Lauer’s absence. Kotb currently co-anchors Today‘s fourth hour with Kathie Lee Gifford, while Guthrie took over as Lauer’s Today co-anchor in 2012 in the wake of Ann Curry’s firing. (Curry was reportedly pushed out by Lauer.)

On Twitter, New York Times television critic James Poniewozik opined that NBC’s choice of Kotb and Guthrie could be a sign that the network could replace Lauer with a woman, whether that be Kotb or another choice.

https://twitter.com/poniewozik/status/935875879070298112

Meanwhile, some speculation swirled in the wake of Lauer’s firing that Curry could actually make a dramatic return to the Today set five years after an awkward, emotional on-air goodbye that, again, was reportedly spurred by Lauer’s own dislike of her. In response to Lauer’s firing, Curry told People that she’s still “processing” the move, but she offered a statement that reflected on the current trend of prominent men being called out and, in some cases, fired over inappropriate sexual behavior. “We need to move this revolution forward and make our workplaces safe,” Curry said.

While Curry’s return seems unlikely, NBC could be more inclined to find Lauer’s replacement in-house. Earlier this year, former Fox News anchor Megyn Kelly signed a huge contract with NBC that pays her an estimated $18 million per year, which would make her the highest-paid on-air talent at NBC News now that Lauer is gone. It would make sense for NBC to install such a high-profile (and highly-compensated) as Lauer’s replacement, though it is definitely worth noting that Kelly’s transition to morning TV at NBC has been anything but smooth. Early reviews for Megyn Kelly Today have been poor and the show has struggled to add viewers since debuting in September. (On Wednesday, Kelly said publicly that Lauer’s firing “hit close to home” and she remarked that she had “heard rumors about Matt, but that’s all.”)

If NBC does restrict its search to internal talent, there’s also no shortage of options being floated online, from longtime Today show regulars such as Al Roker or Carson Daly to Today weekend co-host Craig Melvin.