The Kayapo (Portuguese: Caiapó) people are indigenous peoples in Brazil, from the plain lands of the Mato Grosso and Pará in Brazil, south of the Amazon Basin and along Rio Xingu and its tributaries.

In 2010, their population was 8,638, which has increased from 7,096 in 2003. Subgroups of the Kayapo include the Xikrin, Gorotire, Mekranoti and Metyktire. Their villages typically consist of a dozen huts. A centrally located hut serves as a meeting place for village men to discuss community issues.

The term Kayapó, also spelled Caiapó or Kaiapó, comes from neighboring peoples and means "those who look like monkeys". This name is probably based on a Kayapó men's ritual involving monkey masks. Their autonym is Mebêngôkre, which means "the men from the water hole/place." Other names for them include Gorotire, Kararaô, Kuben-Kran-Krên, Kôkraimôrô, Mekrãgnoti, Metyktire, and Xikrin.

They speak the Kayapo language, which belongs to the Jê language family.

At one time, mining and logging threatened to destroy the rainforest, and thus their way of life. In retaliation, the Kayapo people used forceful tactics to banish loggers and miners in some areas, as well as to establish themselves as an economic force. Later, they were again threatened by secretive government plans to build a series of hydro-electric dams on their land. Under the leadership of Paulinho Paiakan, the Altamira Gathering was orchestrated by the Kayapo, drawing media attention worldwide. This demonstration, staged at the planned site for the first dam in Altamira, Pará, lasted several days and brought much pressure upon both the World Bank and the Brazilian government.