Nicknamed the 'Black Panther', Eusebio was a European Cup winner with Benfica in 1962 and played in three other finals, including the loss to Manchester United at Wembley in 1968.
Eusebio helped Benfica to 11 Portuguese championships and later served as an 'ambassador' for the club. He scored more than 300 league goals for the Lisbon outfit.
Eusebio, whose full name was Eusebio da Silva Ferreira, was European Footballer of the Year in 1965 but won global acclaim a year later at the World Cup in England, where his nine goals helped Portugal reach the semi-finals.
He won 64 caps and scored 41 goals for Portugal, records that stood for almost two decades before being broken.
At Benfica's stadium in Lisbon on Sunday, fans gathered around a statue of Eusebio to lay tributes and take photographs.
"Eusebio was a national and international figure, the world will be mourning because we have lost not only an exceptional player but also an exceptional man," the winger said. "We had a big complicity between us during for many years, many matches together so I think that I've lost a bit of me too losing this great friend."
Germano Sousa was one of a number of Benfica fans visiting the team's museum when the news of Eusebio's death was announced.
"I came to see the museum and this tragedy happens, for us is a big sadness," Sousa said. "I'm a Benfica fan from forever, I'm very sad but life goes on."