Steven Hendry is the youngest ever. Previous to him it was Alex Higgins.
The current F1 world champion is Sebastian Vettel from Germany. He is the youngest ever world champion.
Iron Mike Tyson was the youngest heavy weight champion ever at 20 years old.
Randy Orton was the youngest World Heavyweight Champion
Ian Thorpe of Australia won four gold medals at the 1998 Commonwealth Games in Kuala Lumpur at the age of 15.
Ian Thorpe of Australia won 4 gold medals in the 1998 Commonwealth Games in Kuala Lumpur at the age of 15
Brock Lesnar won the world heavyweight championship at the age of 24
Wilfredo Benitez won a professional world title when he was 17 years of age