The Estrela Mountain Dog or is a Portuguese breed of large flock guardian dog indigenous to the Serra da Estrela mountain range in central Portugal.
The breed has been developed in the mountains of Serra da Estrela, in what is now Portugal. A breed society, the , was established in Lisbon in December 1986; the statutes of the association were published early the next year in the Diário da República, the official gazette of the Republic.
In the twenty-first century, some of the dogs have been used to protect flocks from Iberian wolves â which are themselves a protected species.