Dom Pedro Mascarenhas (1470 – June 16, 1555) is a Portuguese explorer and colonial administrator.

He is the first European to discover the island of Diego Garcia in the Indian Ocean in 1512.

He also encounters the Indian Ocean island of Mauritius in 1512, although he may not have been the first Portuguese explorer to do so; earlier expeditions by Diogo Dias and Afonso de Albuquerque along with Diogo Fernandes Pereira may have encountered the islands.

In 1528 explorer Diogo Rodrigues (after whom the island of Rodrigues is named) names the islands of Réunion, Mauritius, and Rodrigues the Mascarene Islands, after Mascarenhas.