, commonly known as Kaká (Brazilian Portuguese: [kaˈka] ) or Ricardo Kaká, is a Brazilian former professional footballer who played as an attacking midfielder. In his prime at AC Milan, where he was known for his passing, goalscoring, and dribbling, Kaká was widely regarded as one of the greatest players of his generation. He is also regarded as one of the greatest midfielders in the history of the sport. With success for both club and country, he is one of the nine players to win the FIFA World Cup, the UEFA Champions League, and the Ballon d'Or.

In 2001, at age 18, Kaká made his professional debut at Brazilian club São Paulo. He later joined Italian club AC Milan in 2003. Kaká helped Milan win the Serie A title in his first season. Milan finished runner-up in the 2004–05 UEFA Champions League with Kaká being the top assist provider of the tournament and being named the UEFA Club Midfielder of the Year. He led Milan to win the 2006–07 UEFA Champions League and was the tournament's top goalscorer. His performances saw him win the FIFA World Player of the Year, the 2007 Ballon d'Or, and the UEFA Club Footballer of the Year. After six years with Milan, Kaká joined Real Madrid in 2009 for a transfer fee of €67 million, which was the second highest transfer fee at the time. However, his four seasons in Madrid were plagued with injuries, which saw his pace decline. He returned to AC Milan for a single season in 2013, prior to joining MLS expansion club Orlando City SC. He initially went on loan to his former club São Paulo before returning to Orlando in 2015 and retiring from professional football in 2017.

Kaká made his debut for the Brazil national team in 2002 and was selected for the 2002 FIFA World Cup squad, which won the tournament that year. He also played in the 2006 World Cup, alongside other veterans like Ronaldo, Adriano, and Ronaldinho. He made his final World Cup appearance in 2010. He was also a member of Brazil's 2005 and 2009 FIFA Confederations Cup-winning squads, winning the Golden Ball in 2009 as the tournament's best player.

Between 2006 and 2009, he was named in both the FIFA World XI and the UEFA Team of the Year three times. In 2010, he was named in the AC Milan Hall of Fame. One of the world's most famous athletes during his playing career, Kaká was the first sportsperson to amass 10 million followers on Twitter. Outside of football, Kaká is known for his humanitarian work, where he became the youngest ambassador of the UN World Food Programme in 2004. For his contributions on and off the pitch, Kaká was named by Time as one of the world's 100 most influential people in 2008 and in 2009.