The McLaren MCL33 is a Formula One racing car designed and constructed by McLaren to compete in the 2018 FIA Formula One World Championship. The car was driven by two-time World Drivers' Champion Fernando Alonso and Stoffel Vandoorne, with additional testing and development work carried out by reigning European Formula 3 champion Lando Norris and McLaren's regular test driver Oliver Turvey. The MCL33 is the first car built by McLaren to use a customer Renault engine after the team terminated its engine supply deal with Honda after three years and also first McLaren car to utilize a French-licensed engine manufacturer since the Peugeot-powered McLaren MP4/9 in 1994. It made its competitive debut at the 2018 Australian Grand Prix. The car was launched with an orange and blue livery designed as a tribute to some of the team's earliest cars. Currently Fernando Alonso’s MCL33 is on display at the Petersen Automotive Museum in Los Angeles, CA, USA.

The 2018 FIA Formula One World Championship was the motor racing championship for Formula One cars and the 69th running of the Formula One World Championship. Formula One is recognised by the governing body of international motorsport, the Fédération Internationale de l'Automobile (FIA), as the highest class of competition for open-wheel racing cars. Drivers and teams competed in twenty-one Grands Prix for the World Drivers' and World Constructors' championship titles.