West Ham joint-chairman David Gold has died at the age of 86 following a short illness.
A West Ham statement read: "It is with deep sadness that West Ham United FC confirm that our beloved joint-chairman David Gold passed away on Wednesday morning following a short illness.
"David Gold, 86, died peacefully with his devoted daughters, Jacqueline and Vanessa, and his fiancée Lesley, by his side."
Gold had been in joint charge at West Ham with David Sullivan since 2010, when the pair purchased a controlling stake in the club. He was previously chairman and co-owner of Birmingham City until 2009.
Gold was a lifelong West Ham fan and grew up opposite the Boleyn Ground - the club's former stadium - and played for the club's youth teams.
Sullivan said: "On behalf of everyone at the football club, it is with profound sorrow and a heavy heart that we mourn the passing of our colleague and friend, David Gold.
"Of all our joint ventures, none gave us more pride and happiness than the day we took ownership of West Ham United, our club, in January 2010. David had a long-standing connection with the Hammers, having grown up opposite the Boleyn Ground in Green Street, and represented the club at junior level. He always wanted what was best for West Ham United, and his passing is a great loss for all of us."
Manager David Moyes added: "I am extremely sad to hear this news and, on behalf of all of the players and my staff at the training ground, I would like to extend our deepest sympathies to David Gold's family at this very difficult time.
"Mr Gold was a regular visitor to Rush Green and always a source of great support and encouragement to myself and the players. It was clear that he had a genuine and sincere love for the club and was a true supporter at heart. He took a great interest in the people working behind the scenes and was always keen to help in any way he could. He will be greatly missed."
West Ham vice-chairman Karren Brady tweeted: "To a great man, a great friend for over 30 years and a complete gentleman - you will be missed. Rest in peace."
West Ham travel to Leeds in the Premier League on Wednesday evening.
'An incredible man who loved West Ham'
Sky Sports News chief reporter Kaveh Solhekol:
"He was an incredible man who led an incredible life. He admitted that he grew up in 'abject poverty', those were his words. His life was a rags-to-riches story. He was born and lived across the road from West Ham's old stadium Upton Park. He said his family had absolutely no money.
"He started off working when he was 14 as an apprentice bricklayer to make ends meet. He used to help his mother sell buttons outside Upton Park. He went from that start in life to becoming one of the richest businessmen in the UK.
"He had interests in property, publishing, and retail, he even owned his own airline for a while. Of course, he was very closely involved in football. He had dreams of becoming a footballer when he was young, he used to play for West Ham's youth teams.
"It didn't work out for him as a player but he went on to have a hugely successful career as a co-owner, working closely with his business partners David Sullivan and Karen Brady. First of all, they bought Birmingham City and owned the club for 16 years. The club was almost bankrupt when they bought the club, it was about to be relegated, they turned Birmingham around.
"They sold that club and then a year later in 2010 bought West Ham. He always said the reason he wanted to buy West Ham was for 'emotional reasons' not financial reasons. At times he was a controversial owner of the club but I don't think anyone could deny the fact the club are in a much better state now than when he bought the club with David Sullivan in 2010.
"Gold was the last of a kind. Now in the Premier League a lot of the owners are foreign and do not regularly go to games. They may be buying clubs for financial reasons rather than emotional reasons. He was totally the opposite, he was a West Ham supporter, who loved the club. He used to go to every game home and away even when times were tough and getting abused by West Ham supporters, he was willing to take that on not just in person but on social media as well.
"To deal with personally he was someone who would always speak to you. If you went to Premier League meetings where there would be owners or chief executives from all the clubs there, it was a given that after the meeting David Gold would be one of the few people that would speak to the media. Maybe not always on camera but he would take time to speak to you.
"He was a visible presence at West Ham's training ground. I remember before they moved training grounds, David Gold's helicopter would be there quite regularly. He was a very hands-on owner."