When Barack Obama welcomed a somewhat startled looking Donald Trump to the White House last Thursday, and the two men exchanged words of improbable mutual respect, those who fear the worst out of a Trump administration momentarily appeared to have reason for respite. For it seemed, then and when Trump in the hours that followed indicated that he would retain elements of Obama's healthcare programme, that the President-elect was being tamed.

But any doubts over whether he intends to implement the most extreme, politically incorrect and, frankly sexist agenda set out by any presidential candidate have been laid to rest with the appointment of Stephen Bannon as his head of strategy. The move marks the elevation of the burgeoning 'alt-right' movement – which among other agendas is vociferously opposed to multiculturalism – into the White House itself.

So who is this man, appointed alongside – and 'equal' to – the chairman of the Republican National Committee, Reince Priebus, who was made chief of staff?

Bannon is the former head of Breitbart News, who stood down to work on Trump's campaign. The notorious outlet was launched in 2007 with the aim of being "unapologetically pro-freedom and pro-Israel". A hint at its real agenda comes with the following examples of misogynistic headlines highlighted by @EverydaySexism:

Just a tiny selection of the articles published under Trump's new chief strategist Stephen Bannon pic.twitter.com/jYg4nqUGuP

— EverydaySexism (@EverydaySexism) November 14, 2016

The Anti-Defamation League, which campaigns to fight "anti-Semitism and all forms of bigotry", has condemned Bannon's appointment, describing the alt-right movement supported by Breitbart as "a loose-knit group of white nationalists, unabashed anti-Semites and racists".

Meanwhile, Bannon's elevation has provoked criticism from Trump's own party. John Weaver, a Republican political consultant, said: "The racist, fascist extreme right is represented footsteps from the Oval Office. Be very vigilant America."

And the former Barack Obama adviser Dan Pfeiffer noted: "Nation exhales because white nationalist only gets second most influential job in White House."

Michael Wear, Obama's former faith adviser, told Christian Today: "I worked in The White House, so the idea of having Stephen Bannon in an office anywhere near that building, not to mention right next to the Oval Office, is beyond troubling. Trump says he wants to unite the country, but we've learned he says a lot of things. This action--his hiring of this man who has been so corrosive to our politics and whose views on various communities in America are a disgrace—is another reminder that we the American people need to unite not on the terms of our politicians, but of basic human dignity under God."

In August Bannon was made manager of Trump's campaign, in a move which was celebrated by David Duke, the former KKK leader.

"Many former employees of Breitbart News are afraid of Steve Bannon," said Ben Shapiro, a former editor-at-large of Breitbart, who resigned in disgust at the site's bias in coverage of the race between Hillary Clinton and Trump.

"He is a vindictive, nasty figure, infamous for verbally abusing supposed friends and threatening enemies. Bannon is a smarter version of Trump: he's an aggressive self-promoter who name-drops to heighten his profile and woo bigger names, and then uses those bigger names as stepping stools to his next destination."

Shapiro wrote in August: "Trump may be his final destination. Or it may not. He will attempt to ruin anyone who impedes his unending ambition."

Even his allies accept Bannon is, at the very least, a controversialist. "If there's an explosion or a fire somewhere," said Matthew Boyle, political editor for Breitbart, "Steve's probably nearby with some matches."

A former Goldman Sachs banker, Bannon, 62, gained a Masters in National Security Studies and an MBA from Harvard Business School, and was an officer in the US Navy before joining Breitbart, where he hosted a radio show on its SiriusXM Patriot channel.

Born into a poor family in Norfolk, Virginia, Bannon claims that his background is that of a natural Democrat. He grew up in sight of the naval yard and signed up after college before spending four years at sea aboard a destroyer. Deployed to the Arabian Sea and Persian Gulf in 1979, he found his faith in the then president, Jimmy Carter, fading, according to the Telegraph.

Bannon left the navy and instead studied for an MBA at Harvard Business School before winning a job at Goldman Sachs, one that he loved by all accounts.

But in 1990 he set up his own firm, Bannon & Co., with a couple of former colleagues. The company made him rich, and he moved into Hollywood productions, becoming an executive producer of films including Anthony Hopkins's 1999 Oscar-nominated Titus.

Bannon began making his own films, specialising in stories inspired by the attacks of September 11, 2001 and his own disillusionment with President Carter when he was a sailor.

"I come from a blue-collar, Irish Catholic, pro-Kennedy, pro-union family of Democrats," Bannon told Bloomberg. "I wasn't political until I got into the service and saw how badly Jimmy Carter f----- things up. I became a huge Reagan admirer. Still am. But what turned me against the whole establishment was coming back from running companies in Asia in 2008 and seeing that Bush had f----- up as badly as Carter. The whole country was a disaster."

In 2004, he made a pro-Reagan documentary called In the Face of Evil, which was celebrated by the American right, and he appeared regularly on the Murdoch-owned Fox News channel.

Bannon also produced a documentary about Sarah Palin, who is tipped for a role in Trump's administration, and made films in praise of the 'Tea Party' movement.

Bannon took over the Breitbart website after its founder Andrew Breitbart died of a heart attack in March 2012, aged 43.

The controversial site –  which attracts 21 million hits a month – is described by Bloomberg as "a haven for people who think Fox News is too polite and restrained."

Bannon has been married three times and his second wife, Mary Louise Piccard, accused him of domestic abuse and anti-Semitism.

Piccard said in a 2007 court declaration that Bannon did not want their twin daughters attending the Archer School for Girls in Los Angeles because many Jewish students were enrolled at the school.

"The biggest problem he had with Archer is the number of Jews that attend," Piccard said in a statement to the court. "He said that he doesn't like the way they raise their kids to be 'whiny brats' and that he didn't want the girls going to school with Jews."

Bannon denied the allegations. But that such claims could be made about a man who is to become a senior White House staffer has filled many in Washington – and the wider world – with horror.

If there were people who were afraid of what a Trump administration could bring to America last Wednesday, they  arguably have every reason to be even more so today.