Mr Novak produced an influential column for over four decades
Veteran US newspaper columnist Robert Novak, 78, has died after a battle with brain cancer.
Mr Novak made headlines in 2003 when he revealed the identity of covert CIA agent Valerie Plame in a column.
The leak led to a long-running criminal investigation into senior Bush administration officials.
From 1963 until his retirement in 2008, Mr Novak - a staunch conservative - wrote an influential political column that was syndicated throughout the US.
In 2003, he came under fire for a column in which he revealed that "two senior administration officials" had told him that Valerie Plame - the wife of a US ambassador who had voiced doubts about the Bush administration's case for the war in Iraq - was a CIA operative.
Disclosing the identity of a covert agent is illegal in the US, and as a result of the column a special prosecutor was appointed to look into whether Bush officials had broken the law.
An aide to Vice-President Dick Cheney, Lewis "Scooter" Libby, was eventually convicted of perjury as a consequence of the investigation.
Senate Republican Leader Mitch McConnell paid tribute to Mr Novak, saying he "explained the politics and the personalities of Washington to readers across the country through a mix of tireless shoe leather reporting and the kind of keen insight that can only be gained through years and years of dedication to a craft".
US MEDIA REACTION TO THE DEATH OF ROBERT NOVAK
For decades, his work ethic was legendary, his schedule exhausting. He was a voracious reader. His illness exposed what he held most dear, and that was his family, his faith, his Army service... In the midst of such suffering, there was such grace. Bob Novak was a devoted husband and father, a loving grandfather, a loyal friend - and an extraordinary journalist. He will be missed terribly.
The National Review's Kate O'Beirne
remembers her close friend and colleague.
He was a hard-working reporter long after the age when most journalists have left the field. He was not afraid to be unpopular, which is a deeply impressive quality. He had a loving family. His friends, some of whom I count as friendly acquaintances, say he was actually a nice guy or not as un-nice as he seemed. But there was a lot in Novak not to like, a mean gruff manner visible to anyone on TV, a stiletto pen that seemed more about destroying than illuminating.
The Atlantic's Matthew Cooper, who also became embroiled in the Valerie Plame affair,
presents a mixed picture of Mr Novak.
His columns, while they resided on the op-ed pages, were built upon previously unreported facts that revealed and explained the machinations of government, the men and women in power, and the politics behind it all... Bob Novak was, above all, a reporter. Watching him work was a delightful education in reporting.
Tim Carney, writing at Human Events,
recalls his time working as an assistant to the veteran journalist.
Novak was, to be perfectly honest about it, the least pleasant person I've ever interviewed. He didn't shake my hand upon entering or leaving his office, and expressed fairly open contempt when I asked him a question about the Valerie Plame affair. I don't mean to rag on the guy. It wasn't his job to be pleasant... and I didn't get the sense he tried to give anyone an impression to the contrary.
Conor Clarke, filling in for Andrew Sullivan,
was not a fan of Mr Novak.
Robert Novak, one of the best political columnists and reporters to ever write, has been called home to the Lord today. If you've never read his biography, Prince of Darkness, you really should. Novak was not your typical columnist - he always broke news. That made his writing both unique and in demand.
RedState's Erick Erickson
applauds Mr Novak's journalism.