(Adds Murdoch comments)
NEW YORK, May 18 (Reuters) - Roger Ailes, former chief executive of Fox News, the cable news channel popular with conservatives that helped reshape the U.S. political landscape, has died at age 77.
Ailes' widow, Elizabeth Ailes, announced his death in a statement posted on the Fox News website on Thursday. The cause of death was not immediately known.
Ailes resigned from Fox last July following allegations of sexual harassment, marking an abrupt end to his 20-year reign at one of the most lucrative cable channels in the United States.
Under Ailes, Fox raised the temperature of on-air debate on U.S. television, generally taking a hardline conservative view. It has had a mixed relationship with U.S. President Donald Trump, a longtime friend of Ailes, but was instrumental in his election victory in November.
Fox News is owned by Rupert Murdoch's Twenty-First Century Fox Inc. Ailes received a severance package of about $40 million when he left Fox News, according to a source familiar with the situation, and went on to serve as an informal adviser to Murdoch.
"Everybody at Fox News is shocked and grieved by the death of Roger Ailes," Murdoch said in a statement.
"Roger and I shared a big idea which he executed in a way no one else could have," he added. "Roger was a patriot, who never ceased fighting for his beliefs."
Fox host Sean Hannity paid tribute to his former boss.
Today America lost one of its great patriotic warriors," he said in a statement read on the channel. "For decades, RA (Roger Ailes) has impacted American politics and media. He has dramatically and forever changed the political and the media landscape single-handedly for the better."
Democrats also weighed in on someone they often saw as a foe. "I knew Ailes. Competed against him in campaigns," said David Axelrod, ex-adviser to former President Barack Obama, on Twitter. "Railed against him many times. But appreciated our frank, back-channel conversations."
Neither Ailes' wife nor Fox released any details on the circumstances of his death. He suffered from hemophilia, according to a source familiar with the matter.
Gabriel Sherman, a reporter who wrote a biography of Ailes, said on Twitter that Ailes died after suffering a blood clot after falling in Palm Beach, Florida, citing two family friends. Reuters could not immediately confirm Sherman's report.
Fox has been roiled by sexual harassment claims, which also forced the departure of its most-watched host, Bill O'Reilly, in April after the New York Times reported that Fox and O'Reilly had paid five women a total of $13 million to settle harassment claims.
Bill Shine, co-president of Fox News Channel, who had been at the channel since its inception, also left earlier this month.
Despite the high-profile departures, Fox News ratings have remained strong. (Additional reporting by Jonathan Allen, Anna Driver and Jill Serjeant; Writing by Bill Rigby; Editing by Alden Bentley and Jeffrey Benkoe)