Former Formula 1 boss and privacy campaigner Max Mosley has died after suffering from cancer, aged 81.
Ex-F1 chief executive Bernie Ecclestone confirmed the news, saying he died on Sunday.
"He was like family to me," Mr Ecclestone said. "We were like brothers. I am pleased in a way because he suffered for too long."
As well as his years serving as one of the leading figures at the top of the motorsport world, Mr Mosley was also known for his campaigning efforts to strengthen press regulation.
He famously took the News Of The World to court in 2008 after the newspaper printed allegations about his private life, successfully suing its publisher after it wrongly reported he had attended a "Nazi-themed" sex party.
In 2011, the newspaper was shut down by owner Rupert Murdoch after the revelation that it had intercepted the voicemails of celebrities, crime victims and members of the Royal Family, and Mr Mosley later gave financial backing to the court costs of claimants in some newspaper phone hacking cases.
Born in London on 13 April 1940, Mr Mosley was the youngest son of 1930s British fascist leader Sir Oswald Mosley.
Educated at Oxford, he was a racing driver, a team owner and a lawyer before becoming president of the Fédération Internationale de l'Automobile (FIA), the governing body for Formula 1, in 1993, following previous administrative roles in motorsport. He served four terms as president before standing down in 2009.
Paying tribute, an F1 spokesperson said: "We are saddened to hear that Max Mosley, former FIA President, has passed away. A huge figure in the transition of Formula 1. Our thoughts are with his family and friends at this sad time."
Mr Mosley and Mr Ecclestone were a close-knit double act, running the sport as it grew into a $1 billion business and pushing through much-needed safety measures.
In the wake of the death of Brazilian driver Ayrton Senna in 1994, Mr Mosley instituted widespread reform of safety in the sport. Two years later, in 1996, he led the FIA's successful campaign to modernise and strengthen EU crash test standards for the first time since 1974.
He received many government and industry awards, most notably the National de la Légion d'Honneur' in 2006, in recognition of his contribution to road safety and motorsport.
Current FIA president Jean Todt said in a statement posted on social media: "Deeply saddened by the passing of Max Mosley. He was a major figure in @F1 & motor sport. As @FIA President for 16 years, he strongly contributed to reinforcing safety on track & on the roads. The entire FIA community pays tribute to him. Our thoughts & prayers are with his family."