Robert Novak, the conservative columnist and ubiquitous cable pundit who in recent years found himself a central figure in the Valerie Plame scandal, died Tuesday after a yearlong battle with brain cancer. He was 78.

Novak, who died at his home in Washington, D.C., was a face familiar to viewers as one of the original personalities on CNN, where over a 25-year span he appeared on such shows as “Crossfire,” “Evans and Novak” and “The Capital Gang.”

Novak was a fixture in Washington for decades. His relentless sourcing helped him break substantial and controversial scoops in a column syndicated by the Chicago Sun-Times.

“He was a reporter first, and he may have been for decades one of the best sourced reporters, with both parties,” recalled Sam Feist, CNN’s vice president of D.C. programming, who was an intern in 1989 when he first worked for Novak. “Nothing made Bob Novak happier than to publish a scoop in his column.”

It was in 1980 that CNN founder Ted Turner tapped Novak and Rowland Evans, his longtime collaborator, to appear on the nascent cable network. Their show, “Evans and Novak,” foreshadowed cable’s frequent use of Washington insiders. With a liberal counterpart, Novak frequently co-hosted “Crossfire,” which helped set the stage for landscape of sparring talking heads and pundits.

Nicknamed “the Prince of Darkness” by a friend early in his career, for an often cynical and pessimistic outlook, Novak actually embraced the phrase and even used it as the title of his 2007 autobiography.

Weekly Standard executive editor Fred Barnes, who called Novak a mentor, wrote Tuesday that Novak “terrified Washington.”

“Elected and appointed officials, Democrats and Republicans, lobbyists and self-styled defenders of the ‘public interest’ — few were comfortable when Novak had them in his sights. Nor should they have been. The reason was simple: Bob Novak didn’t play political games.”

Mark Shields, moderator and panelist on “Capital Gang” and someone with whom Novak frequently sparred, wrote last year that “although his public ‘game face’ is a scowl, it will pain his critics to learn (Novak) is an exceptionally generous human being whose acts of charity are literally countless.”

While Novak grew more conservative over the years, popularizing supply-side economics, he didn’t not fall in lockstep behind Republicans. For instance, he opposed President Bush’s decision to invade Iraq.

Months after the invasion, and citing two administration sources, Novak wrote a column that identified Valerie Plame as a CIA operative, blowing her cover and leading to a lengthy investigation of who leaked the information. Novak came under fire for the episode. He was subpoenaed and testified before a grand jury but was not prosecuted by special prosecutor Patrick Fitzgerald.

“He never apologized for that column or for naming Valerie Plame,” CNN’s Feist said. “He believed it was a story that needed to be told.”

Born and raised in Joliet, Ill., Novak worked as a stringer for the local paper in high school and later for the Champaign-Urbana paper while attending the U. of Illinois. After college and serving Stateside in the U.S. Army during the Korean War, he landed a job at the Associated Press in Omaha, Neb. That eventually landed him in Washington, where he moved to the Wall Street Journal as chief congressional correspondent. In 1963, he teamed with Evans to write a newspaper column that ran for the next 30 years, when Evans scaled back his workload. Novak continued to write the column until he was diagnosed with a brain tumor last summer.

Novak is survived by his wife, Geraldine, who was a secretary for Lyndon Johnson; their daughter and a son.

(The Associated Press contributed to this report.)