His family confirmed the news on Monday, saying Keegan passed away surrounded by his wife and daughters.
"It is with immense sadness that we announce that Kevin Keegan has passed away at the age of 75," the family said in a statement. "The former England player and manager had been battling cancer and was surrounded by his wife and daughters in his final moments."
Keegan's illness was made public in January, with his family later revealing in June that the cancer had progressed to stage four.
One of the defining figures of English football, Keegan enjoyed a distinguished playing career spanning almost 750 club appearances. After beginning at Scunthorpe United, he joined Liverpool in 1971 and became a key figure in one of the club's most successful eras, winning three First Division titles, the FA Cup, two UEFA Cups and the 1977 European Cup.
His move to German side Hamburg elevated him to global stardom as he claimed back-to-back Ballon d'Or awards in 1978 and 1979, remaining the only British player to have won the prestigious honour twice. He later played for Southampton and Newcastle before retiring in 1984.
On the international stage, Keegan earned 63 England caps, scoring 21 goals and captaining his country 31 times before later returning as national team manager between 1999 and 2000.
Keegan also left an enduring legacy in management, particularly at Newcastle. Appointed in 1992 with the club battling relegation from the second tier, he transformed the Magpies into one of English football's most exciting teams, leading them to promotion before taking them to within touching distance of the 1995-96 Premier League title.
Although Newcastle surrendered a 12-point lead to eventual champions Manchester United, Keegan's attacking philosophy earned his side the nickname "The Entertainers" and cemented his status as a club icon.
He later managed Fulham, England and Manchester City, guiding City back to the Premier League as Division One champions in 2002. A brief second spell at Newcastle in 2008 ended after disagreements with the club's hierarchy.
Tributes poured in from across football following news of his death.
Newcastle described Keegan as "one of the most iconic, influential and deeply loved figures in our club's history", adding that his impact extended far beyond results.
"As a manager, he ignited our city. Kevin gave supporters hope and pride, and led a team whose style, spirit and passion captured the imagination of football fans around the world."
Liverpool also paid tribute to their former forward, saying: "Our 'Mighty Mouse', his legacy at Liverpool will be forever etched in history."
England confirmed the national team will honour Keegan's life before their Nations League match against Spain at Wembley in September, while former Newcastle striker Alan Shearer wrote on social media: "My hero. My manager. My friend. Sleep easy Boss."
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Aston Villa have stepped up their midfield overhaul by completing the 38 million pounds signing of Joao Gomes from Wolves, with the Brazilian becoming the club's second major midfield arrival in the space of a week.
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