Carlos Sainz Vázquez de Castro (Spanish pronunciation: [ˈkaɾlos ˈsajnθ ˈβaθkeθ ðe ˈkastɾo] ; born 1 September 1994) is a Spanish racing driver, who is set to compete in Formula One for Williams. Sainz has won four Formula One Grands Prix across 10 seasons.

Born in Madrid, Sainz is the son of two-time World Rally Champion Carlos Sainz. Graduating from karting to junior formulae in 2010, Sainz won his first championship at the Formula Renault NEC in 2011 with Koiranen, finishing runner-up to Robin Frijns in the Eurocup that year. In 2012, Sainz contested British Formula 3, the Formula 3 Euro Series and FIA European Formula 3 with Carlin. Sainz progressed to the GP3 Series with Arden in 2013, finishing tenth in his rookie season. He then found success in the Formula Renault 3.5 Series, winning the championship in 2014 with DAMS.

A member of the Red Bull Junior Team since 2010, Sainz signed with Toro Rosso in 2015, debuting alongside Max Verstappen. He remained at Toro Rosso until the 2017 United States Grand Prix, where he replaced Jolyon Palmer at Renault, having already signed with the team from 2018 onwards. Sainz moved to McLaren in 2019, ending his association with Red Bull. He took his maiden podium at the Brazilian Grand Prix that year, followed by another at the Italian Grand Prix in 2020. Sainz signed for Ferrari in 2021, replacing Sebastian Vettel to partner Charles Leclerc. After a winless debut season for Ferrari, Sainz took his maiden pole position and win at the British Grand Prix in 2022. He took further wins for Ferrari at Singapore in 2023, as well as Australia and Mexico City in 2024.

As of the 2024 Abu Dhabi Grand Prix, Sainz has achieved four race wins, six pole positions, four fastest laps and 27 podiums in Formula One. Sainz left Ferrari at the end of the 2024 season to join Williams.