Mario Alberto Kempes Chiodi (Spanish pronunciation: [ˈmaɾjo alˈβeɾto ˈkempes ˈtʃjoði], Italian: [ˈkjɔːdi]; born 15 July 1954) is an Argentine former professional footballer who played as a striker or attacking midfielder. A prolific goalscorer, he finished as La Liga's top goalscorer twice with Valencia where he amassed 116 goals in 184 league games. He is regarded as one of the greatest players of all time.

At international level, Kempes was the focal point of Argentina's 1978 World Cup win where he scored twice in the final and received the Golden Boot as top goalscorer. He also won the Golden Ball for the player of the tournament, making him one of only three players to have won all three awards at a single World Cup, along with Garrincha in 1962 and Paolo Rossi in 1982.

Kempes won South American Footballer of the Year, Onze d'Or European footballer of the Year and World Cup Golden Ball in 1978. In 2004, he was named as one of the Top 125 greatest living footballers as part of FIFA's 100th anniversary celebration. Kempes was nicknamed El Toro and El Matador.

Kempes was born in Bell Ville, Córdoba. His father, Mario Quemp, was of German heritage. His mother, Teresa Chiodi, was Italian. At the age of seven he began playing with a junior team and at fourteen he joined the Talleres reserves.

Kempes' career started at local club Instituto, where he played alongside Osvaldo Ardiles before quickly moving on to Rosario Central, where he established himself as a remarkable goalscorer, scoring 85 goals in 105 matches, prompting Valencia to sign him. At Mestalla he would go on to win the Copa del Rey, the European Cup Winners' Cup and the UEFA Super Cup as well as two consecutive Pichichis, scoring 24 and 28 goals in the 1976–77 and 1977–78 seasons. Famous as a hard-working forward, he used to strike from outside the penalty area with his surging runs towards goal and was not the traditional center-forward operating solely inside the box. Many defenders found difficulty handling his attacking style.

Before the 1978 World Cup, Kempes was the only foreign-based player on the list of coach César Luis Menotti's Argentina national team. when announcing the squad he had selected for the 1978 tournament, Menotti described him with these words: "He's strong, he's got skill, he creates spaces and he shoots hard. He's a player who can make a difference, and he can play in a centre-forward position."

Kempes had been the top scorer in La Liga the previous two seasons and was determined to show on home soil that he could deliver against the best on the sport's greatest stage. However, he had failed to get on the score-sheet in West Germany in 1974, at the age of 19, and after the first round group stage in 1978, his name was still missing among goal scorers in the tournament.

After leaving Valencia in 1984, Kempes spent two years at Hércules in nearby Alicante before spending six years at various Austrian clubs. His play declined in his 30s and he did not compete for top scorer honours in the Austrian top flight. He rounded off his career with stints at more obscure clubs in Indonesia, Chile and Albania during the 1990s.