Arnao Esterlin (c. 1510 – 1593) was a Flemish conquistador in service of the Spanish crown.

He took part in the appointment of Captain Domingo Martínez de Irala as lieutenant governor of Asuncion.

[1] Esterlin was born in Flanders, the son of Cristóbal Esterlin (Osterling) and Ana Bersthin, natives of Germany.

[2] Arnao Esterlin had three natural children with a Guaraní woman, native of Asunción.

[3] His son Rodrigo de Esterlín, was married to Juana Solorzano, the daughter of Zoilo de Solorzano, a conqueror born in Biscay.