The 'grandfather of Gogglebox' Leon Bernicoff has died in hospital aged 83 after a short illness.
In a statement Channel 4 paid tribute to the retired teacher who with his "unique personality and wit" was an audience favourite.
Channel 4 and Studio Lambert said: "It is with a heavy heart that we announce the sad news that after a short illness Gogglebox's Leon Bernicoff passed away in hospital earlier today.
"Leon's unique personality and sharp wit endeared him to fans of the show, as he contributed fully to Gogglebox's reputation as a programme full of warm humour and unvarnished opinion.
"To those of us that knew him personally, Leon was a man of unwavering principles who exerted a distinct paternal presence both on and off screen. He will be dearly missed by the entire Gogglebox family; cast and crew."
Gogglebox creator Tania Alexander tweeted: "So deeply saddened at the passing of our dear, dear Leon. He was and always will be the grandfather of #gogglebox - an absolute star who always made me laugh with his sharp wit and unshakable opinions. Much love and strength to June."
Mr Bernicoff and his wife June were one of the first couples to join the cast of the show in 2013 appearing in all 10 series in which they shared their reactions and heartfelt musings to popular TV shows.
Fellow Gogglebox stars Scott and Georgia McCormick and Scarlett Moffatt expressed their sadness at news of his passing.
"Words can't explain what you meant to so many people," said Moffatt in an emotional tweet.
Fans of the show have also taken to Twitter to share their memories of Mr Bernicoff most memorable moments on the TV show.
Born on October 27 1934, Mr Bernicoff is survived by his wife, two daughters, sons-in-law and grandchildren, BBC News reports.