Diogo de Couto (about 1542 – Goa, December 10, 1616) was a portuguese historian.
He was born in Lisbon in 1542 and studied Latin and Rhetoric at Saint Antão College and philosophy at the convent at Benfica. In 1559 he traveled to India, whence he would not return for a decade.
He was a close friend of the poet Luís de Camões, and described him in Ilha de Moçambique in 1569, indebted and unable to fund his return to Portugal. De Couto and other friends took it upon themselves to help Camões, who was thus enabled to take his most significant work, the Lusiads, to the capital. Do Couto arrived in Lisbon on board the Santa Clara in April 1570, only to discover that the port was closed due to plague. Upon receiving permission from the King of Portugal, the ship docked in Tejo.