Leyton Orient manager Justin Edinburgh has died at the age of 49 - five days after suffering a cardiac arrest.
Edinburgh, who guided Orient back into the English Football League in 2018-19, had been taken to hospital on Monday.
"We are completely heartbroken by this tragedy," Orient chairman Nigel Travis told the club's website.
Edinburgh, who won the FA Cup as a Spurs player, managed Northampton Town, Gillingham and Newport County before moving to Orient in November 2017.
"All our thoughts and love are with the Edinburgh family and we know from the messages that have flooded into the club over the last week that the wider football world will share our sentiments," added Travis.
"The success that Justin brought to Leyton Orient was incredible, but more importantly the impact he had on us all as a winner and a wonderful, inspirational human being will be his legacy and will stay with us forever.
"All our thoughts are with Justin's wife Kerri and their children Charlie and Cydnie."
Success as player and manager
After turning professional at Southend, Edinburgh - a left-back - spent a decade playing for Tottenham, making 258 appearances and winning the FA Cup in 1991 and League Cup in 1999 before moving to Portsmouth.
He became player-manager of non-league Billericay Town in 2003 before spells at Fisher Athletic and Rushden and Diamonds.
His managerial breakthrough came at Newport County, whom he led to promotion to League Two in 2013 having guided them to the FA Trophy final a year earlier.
A 23-month spell at Gillingham from January 2015 followed, before nine months at Northampton in 2016-2017.
He was appointed Orient boss in November of 2017, and led the club to 45 wins in his 82 games in charge.
Orient pay tribute to 'amazing and inspirational' Edinburgh
Orient captain Jobi McAnuff tweeted a picture of himself and Edinburgh celebrating this season's National League title, saying: "Totally and utterly devastated. You were so much more than a manager to me.
"Just doesn't feel real coming so soon after sharing some of my happiest moments with you. My thoughts, love and prayers go to the family at this truly terrible time. R.I.P Justin."
Orient striker Macauley Bonne tweeted: "There are no words to describe the loss of our gaffer, our leader & inspiration. He brought us all together - we're eternally grateful for everything you've done."
Fellow forward James Alabi said he was "absolutely broken" while defender Jamie Turley said he was: "Devastated and lost for words at the loss of this great man. It was an honour to play for him. Truly an amazing and inspirational person in all aspects."
Defender Marvin Ekpiteta tweeted he was "lost for words" while winger James Brophy posted: "A wonderful man, who had a positive impact on everyone he met no matter how much time you'd spent with him! Never be forgotten! Thank you for everything."
Leyton Orient Fans' Trust said in a statement that in his 18 months at the club, "Justin became an Orient legend".
They added: "When Justin arrived, the team was still struggling but his shrewd and tenacious management helped turn our performances around and give us a team we could be proud of - one of the most likeable Orient teams we have known.
"He was clearly deeply liked and admired by his players, who owe him a great deal."
Former Orient chairman Barry Hearn tweeted: "Words fall short of the sadness this news brings. A lovely man who achieved so much for Leyton Orient. He shall not be forgotten."
BBC London's Orient reporter Dave Victor, who has reported on the club for several years, tweeted: "It was an enormous pleasure and a privilege to have known and worked with him.
"Justin achieved so much with The O's and we knew it was just the beginning."
'Players adored him and journalists loved him'
BBC Sport Wales reporter Michael Pearlman, who covered Newport County for the local newspaper when Justin was manager:
It is no surprise to see such a rush from people within football paying tribute to Justin Edinburgh.
While he spent virtually his entire playing career at the top level, Edinburgh had to do it the tough way in management, starting at the bottom.
Because of his character and ability, Edinburgh thrived at Billericay, Fisher and Rushden before I encountered him when he arrived at Newport County.
Just as he did with Orient - either side of spells at Gillingham and Northampton - he took a club on its knees and made it proud again, going from relegation worries to promotion in unthinkably quick time.
Players adored him because he knew how they wanted to be treated, and we as journalists loved him because whatever the result, he was always happy to be available and accountable, happy to talk morning, noon or night. He even texted me on my wedding day.
I saw him go above and beyond in giving his time to supporters and the community time and time again and will remember him very fondly for his sense of humour, passion for football and, mainly, his dedication to his family.
His loss will be felt enormously.
Tottenham's 1991 FA Cup winners 'devastated'
Edinburgh was in the Spurs side that beat Nottingham Forest in the 1991 FA Cup final.
Gary Lineker, a team-mate that day and now BBC Match of the Day presenter, tweeted: "Deeply saddened to hear that Justin Edinburgh has passed away.
"He was an excellent coach and a terrific full-back who was a delight to share a dressing room with and have as a team-mate."
Former Spurs captain Ledley King posted: "I can't believe this. Saw Justin last week and he was in great shape and full of life. He was genuinely one of the nicest guys you could meet. Thoughts and prayers to his family. RIP mate."
Paul Stewart, who scored Spurs' equaliser in the 1991 final said he was "gutted" while Steve Sedgley tweeted: "Devastated, A sad, sad, day, a truly great person."
Another former Tottenham teammate, David Ginola, tweeted: "Justin Edinburgh....deeply shocked, deeply saddened... RIP my friend, I shall miss you."
Meanwhile, former Spurs player and manager Glenn Hoddle tweeted he was "devastated" by "the very sad and tragic news".
Tributes to 'a true professional' and 'wonderful man'
Edinburgh's former clubs were also among those to express their grief.
Southend, his first team as a player, sent their "thoughts and heartfelt condolences" to Edinburgh's family and friends and "everyone at Leyton Orient".
Newport County said they were "stunned and devastated" by the news, while Northampton Town said: "Everyone at Northampton Town Football Club is shocked and deeply saddened."
Portsmouth said they were "shocked and saddened", adding: "Everyone at Pompey would like to send their deepest condolences to Justin's wife Kerri, their children, and his family and friends at this difficult time."
Gillingham tweeted: "The thoughts of everybody at Gillingham Football Club are with Justin Edinburgh's friends, family and colleagues at Leyton Orient at this very difficult time. Such sad news. RIP Justin Edinburgh."
League Managers' Association chairman Howard Wilkinson said: "Justin will be remembered by all in the game as a true professional. A hard-working man who became successful as a player at the highest level of the game and turned his love of football into a lifelong career as a coach and as a manager."
Gary Neville, who co-owns Salford City - who were beaten to the National League title by Orient - described Edinburgh as "a champion that managed a team that played with your spirit".
Carlisle United director of football David Holdsworth said: "Justin was a close personal friend and everyone is devastated at this news.
"He was a football man through and through and an extremely professional and well-respected player and manager. Words can't explain how sad we are and our thoughts are with his family and friends."