Filippo Sassetti (1540–1588) was a traveller and merchant from a long-established Florentine mercantile family, who was born in Florence in 1540.

Though his father had sold family interests and he had to commence as a clerk in a merchant business, Sassetti enrolled in 1568 at the University of Pisa and was imbued with a humanist education; he was proficient in botany, geography, astronomy and cosmography and was curious about philology and the classical languages.

He is known to posterity from the thirty-two detailed letters[1] he sent home to members of the Florentine patriciate and the Grand Duke of Tuscany; they were not published until centuries after his death.

Writing privately to fellow Florentine Bernardo Davanzati in 1585, he noted some word similarities between Sanskrit and Italian (e.g. deva/dio 'God', sarpa/serpe 'snake', sapta/sette 'seven', ashta/otto 'eight', nava/nove 'nine').

[2] This unpublished observation is today credited to have foreshadowed the later discovery of the Indo-European language family.