Stefan Bellof (20 November 1957 – 1 September 1985) was a German racing driver. Bellof was the winner of the Drivers' Championship in the 1984 FIA World Endurance Championship, driving for the factory Rothmans Porsche team. His lap record on the Nordschleife configuration at the Nürburgring, set while qualifying for the 1000 km race in 1983, stood for 35 years, when it was beaten by Timo Bernhard in 2018. He also competed in Formula One with Tyrrell Racing during 1984 and 1985. Bellof was killed in an accident during the 1985 1000 km of Spa, a round of the 1985 World Sportscar Championship.

Born in Gießen, West Germany, and following in his brother Georg's footsteps, Stefan Bellof made his karting début in 1973, competing in the Automobilclub von Deutschland's Federal Junior Cup, in which he ended up in fourth position. Several other top-five championship placings occurred during the next few years before Bellof claimed his first karting title, by winning the International Karting Championship of Luxembourg in 1976. In the same season, Bellof also finished thirteenth in the Karting World Championship in Hagen, Germany. Georg won the German Karting Championship in 1978, while Stefan finished in eighth position in the same race, improving to third in 1979 and becoming German champion in 1980, while dovetailing a campaign in Formula Ford.

Bellof moved into Formula Ford at the tail end of the 1979 season, as a member of Walter Lechner's Racing School setup, making his bow at Hockenheim in November 1979, where he finished in second place. A full season in the 1600cc class beckoned in 1980, and Bellof became champion taking eight victories and nine podium placings from twelve races. He continued in the series in 1981, but was not as successful as his championship-winning season, taking five wins and also made a foray into the more powerful 2000cc class, but retired from both his starts in the Lion Trophy at Zolder and the 300 km meeting at the Nürburgring. Bellof also contested three VW Castrol Europa Pokal races, of which he won one. He also raced at Hockenheim in the European Renault 5 Turbo Cup but retired.

As well as those outings, Bellof moved into the German Formula Three Championship, making his début for Bertram Schäfer's team at Wunstorf. Despite missing the opening two races of the season, Bellof led the championship by seven points going into the final round at the Nürburgring, having taken a top four finish in each of his first eight races. Luck eluded Bellof however, as he finished the race in thirteenth position, while title rivals Frank Jelinski and Franz Konrad finished in first and second places to overhaul Bellof's points total. Eleven points separated Bellof from Jelinski, who claimed his second successive German Formula Three championship. At the conclusion of the season, Bellof contested the Formula Ford Festival at Brands Hatch, but was excluded from the meeting after finishing sixth in his quarter-final heat, for excessive contact. Bellof made a promise to the meeting's clerk of the course, saying that the official had "better watch my career, because I'll be back here next year and I'll win my first Formula 2 race."

Bellof joined Mike Thackwell and Alain Ferté at a test session with Maurer Motorsport at Circuit Paul Ricard in France at the end of the 1981 season. Eje Elgh, who finished third with Maurer in the 1981 European Formula Two Championship was present at the test and was impressed by Bellof, and recommended him to team boss Willy Maurer to sign him for the 1982 season. After acquiring a limited amount of BMW backing, Bellof assumed a place in the team, with Maurer eventually becoming his manager, having signed an eight-year management deal with Bellof.

The first race of the season was the BRDC International Trophy at Silverstone, where Bellof qualified ninth on the grid. Sticking to his promise that he made at the 1981 Formula Ford Festival, Bellof drove through the field in showery conditions to win by 21 seconds ahead of Satoru Nakajima and became the first driver to win outright, and second driver to win a race on his European Formula Two début after Dave Morgan won on aggregate at Silverstone in 1972. He followed this win up with a second successive triumph at the Jim Clark Gedächtnisrennen at Hockenheim, having started from pole position and achieved the fastest lap during the race. Two points from the next six races ruled him out of the championship hunt, as he fell to an eventual fourth place classification, scoring 33 points.

By comparison to his 1982 season, Bellof's 1983 season was much less successful. He made only one trip to the podium with second at Jarama while he lost another podium when he was disqualified from third place at the Pau Grand Prix, after his and teammate Ferté's cars were found to be underweight at the race's conclusion. Bellof's only other points-scoring finish was fourth at Silverstone, as he finished the season in ninth position on nine points.

While competing in Formula Two in 1982, Bellof made a one-off appearance in the World Endurance Championship at the 1000 km of Spa, partnering Rolf Stommelen at the wheel of a Kremer CK5. The pairing retired from the race on lap 51, due to a problem with the starter motor. The previous weekend, Bellof had joined Kremer to compete in the Hessen Cup at Hockenheim as part of the Deutsche Rennsport Meisterschaft, but retired with transmission failure.