In 1993, when King paired Al Gore and Ross Perot for a debate about NAFTA, he set a cable news ratings record that still stands: 16.3 million viewers.
"He helped change the course of an election in 1992 with Ross Perot, getting him to announce his campaign on his show," says Haddad, his former producer. "He was the first talk show host on cable news who proved you could get an audience with interviews and talking about news."
King, who repeatedly remarked on Tuesday's show that he wanted to spend more time with his family, had also recently been having widely publicized difficulties with his seventh wife, Shawn Southwick.
King filed for divorce from Southwick, 50, April 14 in Los Angeles Superior Court, citing "irreconcilable differences" and asking for joint custody of their children.
But a week later the two were said to be back together and in counseling. In May 2010, Southwick overdosed on prescription pills.
Whatever the reason for his departure, King has said that if it were up to him, American Idol emcee Ryan Seacrest would be his choice to fill his shoes, according to The Associated Press. Earlier this month the New York Post reported that CBS anchorwoman Katie Couric, whose own contract is set to expire, is not interested in King's job. Also widely speculated as a potential replacement is Piers Morgan, the former tabloid newspaper editor and winner of Celebrity Apprentice.
Whoever ends up in King's chair, one thing is clear: he or she will have a mighty large pair of suspenders to fill.