Nykänen, one of the sport's most legendary names, won four Olympic titles during his career including a clean sweep of the normal hill, large hill and team golds at Calgary 1988.

He also won large hill gold at Sarajevo 1984, where he clinched normal hill silver.

Nicknamed the Flying Finn, Nykänen's career also included five World Championship gold medals, four overall World Cup titles and one Ski Flying World Championship title.

He won 46 World Cup legs and triumphed at the prestigious Four Hills Tournament twice - meaning he captured every major prize in the sport.

No cause of death has yet been announced, with International Olympic Committee President Thomas Bach among those to pay tribute.

"Matti Nykänen was one of the most successful ski jumpers of history with four Olympic gold medals whose great performances I remember very well," the German said. 

"He is a legend of his sport. 

"Our thoughts are with his family and his friends."

After retirement, Nykänen battled against alcohol and violent behaviour, garnering much media attention for his personal life.

He was twice jailed - firstly for 26 months in 2004 for stabbing a friend and then again for 16 months in 2009 after he assaulted his wife.

He was married five times and launched a singing career, releasing three albums and performing in Helsinki as recently as Friday (February 1).

Nykänen also worked as a stripper during a period of financial hardship.  

His home town of Jyväskylä, where there is a ski jump named after him, held a minute's silence today.

Former Finnish Prime Minister Alexander Stubb said to News Now Finland: "Sad to hear that one of the greatest ski jumpers of all time, Matti Nykänen, has passed away at the age of 55. 

"A legend in so many ways. 

"He will always have a special place in the hearts of winter sports fans around the world."

His long-term coach Matti Pulli described Nykänen as "the best ski jumper ever".

"His structure was excellent, he had very good thrust and he was persistent," Pulli said, according to BBC Sport.

"He was child-like, almost like a cherub, and that charmed people."