Ayrton Senna da Silva (Brazilian Portuguese: [aˈiʁtõ ˈsẽnɐ dɐ ˈsiwvɐ] ^ⓘ; 21 March 1960 – 1 May 1994) was a Brazilian racing driver who competed in Formula One from 1984 to 1994. Senna won three Formula One World Drivers' Championship titles with McLaren, and—at the time of his death—held the record for most pole positions (65), among others; he won 41 Grands Prix across 11 seasons.

Born and raised in São Paulo, Senna began competitive kart racing aged 13; his first go-kart was built by his father using a lawnmower engine. After twice finishing runner-up at the Karting World Championship, Senna progressed to Formula Ford in 1981, dominating the British and European championships in his debut seasons. He then won the 1983 British Formula Three Championship amidst a close title battle with Martin Brundle, further winning the Macau Grand Prix that year. Senna signed for Toleman in 1984, making his Formula One debut at the Brazilian Grand Prix. After scoring several podium finishes in his rookie season, Senna moved to Lotus in 1985 to replace Nigel Mansell, taking his maiden pole position and victory at the rain-affected Portuguese Grand Prix, a feat he repeated in Belgium. He remained at Lotus for his 1986 and 1987 campaigns, scoring multiple wins in each and finishing third in the latter World Drivers' Championship.

Senna signed for McLaren in 1988 to partner Alain Prost; together, they won 15 of 16 Grands Prix held that season—driving the Honda-powered MP4/4—with Senna taking his maiden championship by three points after winning a then-record eight Grands Prix. Their fierce rivalry culminated in title-deciding collisions at Suzuka in 1989 and 1990, despite Prost's move to Ferrari in the latter, with Prost winning the former title and Senna taking the following. Senna took seven victories, including his home Grand Prix in Brazil, as he secured his third title in 1991. The dominant Williams–Renault combination prevailed throughout his remaining two seasons at McLaren, with Senna achieving several race wins in each, including his record-breaking sixth Monaco Grand Prix victory in 1993 on his way to again finishing runner-up to Prost in the championship. Senna negotiated a move to Williams for his 1994 campaign, replacing the retired Prost to partner Damon Hill.

During the 1994 San Marino Grand Prix at Imola, Senna was killed in a crash whilst leading the race, driving the Williams FW16. His state funeral was attended by over a million people. Following subsequent safety reforms, he was the last fatality in the Formula One World Championship until Jules Bianchi in 2015. Senna achieved 41 wins, 65 pole positions, 19 fastest laps and 80 podiums in Formula One; he remains a legendary figure within motorsport for his raw speed and uncompromising driving style, as well as his philanthropy, and is frequently cited as a national hero of Brazil. He was also widely acclaimed for his wet-weather performances, such as at the 1984 Monaco, 1985 Portuguese and 1993 European Grands Prix. Senna was inducted into the International Motorsports Hall of Fame in 2000.

Ayrton Senna was born at 2:35 BRT on 21 March 1960, in the Pro-Matre Maternity Hospital of Santana, a neighbourhood of São Paulo. The middle child of a wealthy Brazilian family, he was born to landowner and factory owner Milton Guirado da Silva and his wife Neide Joanna Senna da Silva; he had an older sister, Viviane, and a younger brother, Leonardo. Senna was of Italian, Spanish, and Portuguese descent: his mother was the granddaughter of Italian immigrants, and his father was the son of a Brazilian father of Portuguese Quatrocentão descent and a Spanish mother from Tíjola, Andalusia.

The house where Senna spent the first four years of his life belonged to his maternal grandfather, João Senna, located less than 100 metres (330 ft) from Campo de Marte, where his family operated the Aeronautics Material park and an airport. Senna was highly athletic—excelling in gymnastics and other sports—and developed an interest in cars and motor racing by the age of four. He had poor motor coordination and had trouble climbing stairways by the age of three; an electroencephalogram showed no abnormalities. Senna's parents nicknamed him Beco. At the age of seven, Senna first learned to drive a Jeep around his family's farm and also how to change gears without using a clutch.

Senna attended the Colégio Rio Branco in the São Paulo neighbourhood of Higienópolis and graduated in 1977 with a grade 5 in physics, alongside other grades in mathematics, chemistry, and English. He later enrolled in a college that specialised in business administration, but dropped out after three months with an average grade of 68%.^{[page needed]}

Senna's first go-kart was built by his father, who operated an automotive factory, using a small 1 hp lawnmower engine. Senna started racing at Interlagos and entered his first kart racing competition at the age of 13.^{[timestamp needed]} He started his debut race on pole position, against drivers who were several years older than him; he managed to lead most of the race before retiring after colliding with an opponent. His father supported him throughout his karting career, with Lucio Pascal Gascon becoming his manager.^{[timestamp needed]}