Curt Unckel, also known as Curt Nimuendajú (18 April 1883 – 10 December 1945), was a German-Brazilian ethnologist, anthropologist and writer. His works are fundamental for the understanding of the religion and cosmology of some native Brazilian Indians, especially the Guarani people. He received the surname "Nimuendajú" from the Apapocuva ramification of the Guarani people, meaning 'the one who made himself a home,' one year after living among them. Upon taking Brazilian citizenship in 1922, he officially added the Nimuendajú as one of his surnames. On his obituary, his Brazilian-German colleague Herbert Baldus called him 'perhaps the greatest Indianista of all time.’
Nimuendajú was born in Wagnergasse 31, Jena, Germany in 1883 and he lost (one or both of his) parents in his childhood. From an early age, he dreamed of living among a 'primitive people'. Still in school, together with other students they organized an 'Indian gang' to go hunting in the woods outside the city. Lacking the financial means to attend a university, he worked in a camera factory run by Carl Zeiss. Meanwhile, he studied maps and the ethnographic studies of the Indian populations of North and South America in his free time. At the age of 20, he emigrated to Brazil in 1903. His half-sister, who was a school teacher, paid for the travel expenses to South America.
Two years after his arrival in Brazil, he contacted some Guaraní people in the State of São Paulo. Although there were many publications on the Guarani since the 17th century, their religious behavior such as rituals was poorly described. Nimuendajú familiarized himself thoroughly with the existing literature. He published “Nimongarai”,(1910) in the German São Paulo newspaper “Deutsche Zeitung”. In 1913, he moved to Belém. In 1914, his groundbreaking publication on the mythology and religion of the Guarani Apapokúva was accepted by the Zeitschrift für Ethnologie. He became a specialist on various Indigenous peoples, particularly on the Gê, as well as Apapocuva-Guaraní, Tukúna, Kaingang, Apinaye, Xerente, Wanano and Canela. His publications laid, in the words of one recent writer: