Marino Ghetaldi (Latin: Marinus Ghetaldus; Croatian: Marin Getaldić; 2 October 1568 – 11 April 1626) was a Ragusan scientist.

He was known for the application of algebra in geometry and his research in the field of geometrical optics on which he wrote 7 works including the Promotus Archimedus (1603) and the De resolutione et compositione mathematica (1630).

He also produced a leaflet with the solutions of 42 geometrical problems, Variorum problematum colletio, in 1607 and set grounds of algebraization of geometry.

Ghetaldi was the constructor of the parabolic mirror (66 cm in diameter), kept today at the National Maritime Museum in London.

Two notable localities in Dubrovnik are associated with the name of Getaldić: Bete's Cave, named after Marino's nickname, where he conducted experiments with igniting mirrors; and Pozvizd, a key strategic tower in the Ston fortification system which he was commissioned to build by the authorities of the Republic of Dubrovnik in 1604.