Steve Bannon has been named as Donald Trump's chief strategist and senior counsel for when he enters the White House in January.
Bannon was the chief of Breitbart News, an "alt-right" news website, from 2012 and gradually gained notoriety within the extreme right wing, dubbed "the vast right-wing conspiracy" by Hillary Clinton.
Prior to working at Breitbart, he worked at Goldman Sachs, before becoming an executive producer in Hollywood.
Under Bannon's leadership, Breitbart has been accused of targeting minorities, the LGBT community, women, Muslims, and immigrants with inflammatory articles.
Headlines created under his leadership include "'Would you rather your child had feminism or cancer?'", "Donald Trump would be the first real black president", and "Does feminism make women ugly?"
He also allegedly dislikes Jewish people, with his ex-wife saying under oath that he did not want their two girls to attend a specific school because of the number of Jewish students.
He "doesn't like the way they raise their kids to be 'whiny brats' and... he didn't want the girls going to school with Jews," she told a court. He has denied the claims.
Another headline under Bannon called conservative Bill Kristol a "renegade Jew", and another suggested that shooting survivor and Democrat politician Gabby Giffords is "the gun control movement's human shield".
Former Breitbart employee Ben Shapiro wrote on his site that Bannon was a "vindictive, nasty figure, infamous for verbally abusing supposed friends and threatening enemies."
Donald Trump said in a statement announcing the appointment: "I am thrilled to have my very successful team continue with me in leading our country.
"Steve [Bannon] and Reince [Priebus] are highly qualified leaders who worked well together on our campaign and led us to a historic victory.
"Now I will have them both with me in the White House as we work to make America great again."