Roger Ailes, the long-time boss of Fox News, has resigned after a number of female employees accused him of sexual harassment.
The network's parent company, 21st Century Fox, announced his resignation.
The announcement does not mention the sexual harassment allegations, which have now come from multiple Fox presenters.
Executive chairman Rupert Murdoch wrote that Mr Ailes has made a "remarkable contribution" to Fox News.
"We continue our commitment to maintaining a work environment based on trust and respect," Fox executives Lachlan Murdoch and James Murdoch said in the statement. "We take seriously our responsibility to uphold these traditional, long-standing values of our company."
Analysis: Nick Bryant, BBC News, New York
Roger Ailes has long been viewed one of America's most powerful conservatives. The one-time media consultant to Richard Nixon was the key figure in building the Fox News channel into a ratings, profits and, most important perhaps, political powerhouse.
Prior to his dramatic and embarrassing downfall, Mr Ailes was said to be one of the few employees that Rupert Murdoch actually feared. But it was the media mogul's admiration for his long-time lieutenant and ideological soul-mate that came through in the warm statement released by Fox News Channel's parent company, 21st Century Fox.
"His grasp of policy and his ability to make profoundly important issues accessible to a broader audience stand in stark contrast to the self-serving elitism that characterises far too much of the media," said Rupert Murdoch, in a tribute that did not touch upon the allegations of sexual harassment against the former news chief. Noticeably, it was left to Mr Murdoch's sons, Lachlan and James, to point out that the company is committed "to maintaining a work environment based on trust and respect."
I'm told by a source close to the company that the Murdochs wanted to move quickly, a lesson learnt from the handling of the phone hacking scandal.
It's also measure of the importance that Mr Murdoch attaches to the Fox News channel that he is personally taking over as chairman and acting CEO after losing one of the central figures in his global media empire. What makes Mr Ailes' departure all the more dramatic is that it should happen on the final day of the Republican convention at a time when a deeply divided conservative movement was already in such a state of flux.
Mr Ailes, 76, said he was stepping down because he had become a "distraction".
"I will not allow my presence to become a distraction from the work that must be done every day," Mr Ailes wrote in a letter to Rupert Murdoch.
He has run Fox News since it launched in 1996 and is credited with reshaping the American media and political landscape.
A veteran of Republican political campaigns, he turned the cable news network into a ratings leader and an influential force in the Republican Party.
"Rupert Murdoch is a conservative, but the Republican intensity, the conservative passion including the viciousness toward the Democrats that we now see against Hillary Clinton and has been going on against Obama all these years, all that is Roger Ailes,'' Paul Levinson, communications professor at Fordham University, told the AP news agency.
Less than two weeks ago former presenter Gretchen Carlson sued Mr Ailes for sexual harassment and wrongful termination, claims he denies.
Ms Carlson, who worked for the network for 11 years, alleges that he proposed having a sexual relationship with her and he instructed her to turn around in his office so he could look at her backside.
Mr Ailes also allegedly called her a "man hater" and that she needed to "get along with the boys".
A report in New York magazine, citing anonymous sources, said lawyers for 21st Century Fox gave Mr Ailes a deadline of 1 August to resign or face being fired.
Further allegations surfaced in US media that Mr Ailes sexually harassed another Fox News presenter, Megyn Kelly, about 10 years ago, claims he has also denied.