As you probably know, Bill O'Reilly was fired by Fox News after it emerged that he and the network had paid multiple women a total of millions of dollars in response to lawsuits for sexual harassment and numerous sponsors had pulled their ads from his show. The network's former head, Roger Ailes, had recently been dismissed over similar allegations.
O'Reilly was the single most watched news show host for many years and a best-selling author of books on history despite widespread criticism of them from academic historians. But he was also notorious for bullying his guests, riling up his viewers with invented controversies (most famously the supposed "war an Christmas"), and exaggerating his own background, claiming for instance saying in his 2001 book The No Spin Zone, "I've reported on the ground in active war zones from El Salvador to the Falklands," and a few years later asserting in a column, "Having survived a combat situation in Argentina during the Falklands war, I know that life-and-death decisions are made in a flash."
He also claimed, "I was in a situation one time, in a war zone in Argentina, in the Falklands, where my photographer got run down and then hit his head and was bleeding from the ear on the concrete. And the army was chasing us. I had to make a decision. And I dragged him off, you know, but at the same time, I’m looking around and trying to do my job, but I figure I had to get this guy out of there because that was more important."
Later, when it was pointed out that the closest he came to the actual Falklands War was Buenos Aires 1200 miles away, O'Reilly insisted, "I never said I was on the Falkland Islands," and that by his reference to the "war zone" he was talking about violent demonstrations in the Argentine capital. But those claims were disputed as well by other reporters present at the time. O'Reilly's response was to imply that the other reporters had been sheltering in their hotel rooms while only he, O'Reilly, had the courage to brave the streets, but in fact other reporters were on the scene. For more on this see Politifact and Salon.
On a more amusing (and stranger) note, I've read that though O'Reilly is a quite tall and imposing, he insisted that his guests sit in shorter chairs in order to make himself look relatively even bigger.
Interestingly, O'Reilly reportedly comes across as much nicer in person, quite friendly and soft-spoken. Stephen Colbert said that O'Reilly once told him his Fox News persona was merely a role he played.
Below The Daily Show and its host Trevor Noah offer a retrospective of O'Reilly mainly in the form of clips that suggest he, or at leasts his television character, could be a pretty nasty person.