Alan Colmes, a host and commentator who had been a mainstay of Fox News since its inception, died Thursday after a brief illness. He was 66.

Colmes was the liberal co-host counterpart to conservative Sean Hannity on the long-running “Hannity and Colmes” program that was part of the inaugural launch slate of Fox News Channel in October 1996.

“I’m truly heartbroken at the loss of a dear friend,” Hannity said in a statement. He called Colmes “one of life’s most decent, kind and wonderful people you’d ever want to meet.”

A New York native, Colmes got his start in the industry as a standup comic after graduating from Hofstra University in 1971. He moved into talk radio in 1984 when he landed a plum drive-time slot on New York’s WABC radio. Three years later he moved to WNBC radio, but the division folded not long after he arrived. Colmes delivered the station’s final sign-off in October 1988.

Colmes hosted programs for New York’s WMCA and Boston’s WZLX before he was tapped for TV at the dawn of the Fox News era in October 1996.

On “Hannity and Colmes,” which came to dominate the 9 p.m. slot among cable news outlets, Colmes was known for his reasoned approach and ample use of humor to express his liberal-leaning views on social and cultural issues. He was well loved by Fox News insiders, even those who were far to the right of his political perspective.

“When Alan and I started ‘Hannity and Colmes,’ there wasn’t a day that went by where we didn’t say we were the two most fortunate men in all television,” Hannity said. “Despite major political differences, we forged a deep friendship. Alan, in the midst of great sickness and illness, showed the single greatest amount of courage I’ve ever seen. And through it all, he showed his incredible wit and humor that was Alan’s signature throughout his entire life.”

Colmes left the show at the end of 2008 as Hannity transitioned into a solo host format. But Colmes remained a regular presence on Fox News as a guest and commentator. Most recently he hosted “The Alan Colmes Show” radio program syndicated by Fox News.

Colmes was the author of 2003’s “Red, White and Liberal: How Left is Right and Right is Wrong” and 2012’s “Thank the Liberals: For Saving America.”

Among those who saluted Colmes was People for the Ethical Treatment of Animals. The org hailed the host for his track recording of devoting air time “to important issues such as circuses, trophy hunting, vegan eating, and more, and he always gave PETA an opportunity to tell the animals’ story. He was a gentle, kind, curious man who will be missed by all of us here at PETA.”

Colmes’ survivors include his wife, Dr. Jocelyn Colmes, who is the sister of Fox News personality Monica Crowley. The two met when she was a guest on “Hannity and Colmes” and were married in 2003.

Colmes’ death comes just three days after the passing of another longtime Fox News personality, Brenda Buttner, host of the “Bulls and Bears” financial news program.