Joseph Siffert (7 July 1936 – 24 October 1971) was a Swiss racing driver.
Affectionately known as "Seppi" to his family and friends, Siffert was born in Fribourg, Switzerland, the son of a dairy owner.
He initially made his name in racing on two wheels, winning the Swiss 350 cc motorcycle championship in 1959, before switching to four wheels with a Formula Junior Stanguellini.
Siffert graduated to Formula One as a privateer in 1962, with a four-cylinder Lotus-Climax.
He later moved to Swiss team Scuderia Filipinetti, and in 1964 joined Rob Walker's private British Rob Walker Racing Team.
Early successes included victories in the non-Championship 1964 and 1965 Mediterranean Grands Prix, both times beating Jim Clark by a very narrow margin.
He won two races in Formula One for the Rob Walker Racing Team and BRM.
He died at the 1971 World Championship Victory Race, having his car roll over after a crash caused by a mechanical failure and being caught under the burning vehicle.
Siffert was married twice and to his second wife Simone during the height of his career in the late 1960s and at the time of his death.
They had two children together, Véronique and Philippe.