British professor Sid Watkins, who tended to Ayrton Senna after the Brazilian's fatal crash at Imola in 1994, has died aged 84.
Watkins served as Formula One's doctor and medical chief between 1978 and 2004.
During his time with the sport he helped countless drivers and was best known as being the doctor on the scene when Senna crashed in the San Marino Grand Prix 18 years ago.
"Motor sport has lost a true visionary and character with death of Prof Sid Watkins. Great man, funny too.Saved my left foot being amputated," said Sky F1's Martin Brundle. "Sid was the 'go to' man for health in Motorsport. He helped, saved, or made more comfortable, numerous people who never sat in a racing car."
"Really sad news that Prof Sid Watkins passed. My heart goes out to his family and friends. Will miss your great sense of humour....R.I.P," tweeted Johnny Herbert.
The current generation of F1 drivers, including McLaren pair Jenson Button and Lewis Hamilton, have also paid tribute.
"Rest in Peace Sid Watkins...Motorsport wouldn't be what it is today without u. Thank you for all you've done, we as drivers are so grateful," said Button.