Eggheads star Dave Rainford has tragically passed away at the age of 51.
It follows David stepping down from the show due to illness last year.
"I'm very sad to hear that one of the Eggheads has died," host Jeremy Vine said on social media today (March 7). "Dave 'Tremendous Knowledge' Rainford, famous for being banned from pub quiz machines in Manchester, was the best company after a recording: always fun and sociable.
"I never saw him angry or ungenerous, not once."
Many others paid tribute, including The Chase's Paul Sinha who tweeted: "Devastated at the loss of my friend David Rainford.
"Egghead, great bloke, great friend. We had blindingly good nights out mate X."
Fellow Chaser Anne Hegerty added: "Very sad to learn that Tremendous Knowledge Dave Rainford of #Eggheads has died. One of the nicest people I ever knew. Never a bad word about anyone."
Taking to Twitter last year, David told viewers he was unable to take part in the latest recordings due to an unspecified illness.
He said: "Brand new Eggheads starting on Monday. I was still recuperating when these programmes were recorded, but I can promise you that there are some great shows coming up with excellent challengers that will keep you on the edge of your seats. Keep watching."
David was one of nine Eggheads who appear on the BBC Two show.
The brainbox, who won £250,000 on Who Wants To Be A Millionaire in 2005, joined the series in 2012.
Other Eggheads are Kevin Ashman, Chris Hughes, Judith Keppel, Barry Simmons, Pat Gibson, David Rainford, Lisa Thiel, Steve Cooke and Beth Webster.
Eggheads currently airs at 6PM on BBC Two.
First airing in 2003, the series has since seen over 1,800 episodes.
The format sees one team of contestants attempt to win a cash prize against a group of the Eggheads, with the prize pot increasing each game until the Eggheads are beaten.
To date the biggest prize won has been £75,000 while almost £2 million in total has been paid out since the first episode aired.
Meanwhile, alongside the main show, there have been a number of spin-offs.
As well as a Celebrity series, these have included Are You an Egghead?, Revenge of the Egghead and Make Me an Egghead.
Currently hosted by Jeremy Vine, you can watch episodes of Eggheads online here via the BBC iPlayer.