|Monarch John V of Portugal||Succeeded by António Cabral|
|Preceded by José Maria da Fonseca de Évora|
Died February 1750, Civitavecchia, Italy
Manuel Pereira de Sampaio (Lagos; 1692 - Rome; February 1750) was a Portuguese nobleman and diplomat, who served as King John V of Portugal's ambassador to the Holy See.
He is remembered notably for having secured the styling of Most Faithful Majesty for the Portuguese monarchy, in 1748, and for compiling what is now known as the Weale Album (Portuguese: Álbum Weale), an extensive catalog of artistic commissions by John V for Lisbon from Rome.
The exact details of his origins are unclear, it is known that Pereira de Sampaio was born in Lagos, in the Algarve, as a bastard of a minor Fidalgo of Portuguese nobility.
He was governor of the Church of Sant'Antonio dei Portoghesi, the Portuguese national church in Rome, and a prominent member of the artistic scene in Rome at the time. His position as governor, his personal reports on Pope Benedict XIV to King John V, and his close relationship with João Baptista Carbone, personal secretary of the Portuguese king, were all deciding factors in his nomination as ambassador to the papal court.
While ambassador, Pereira de Sampaio cataloged the numerous artistic commissions made by King John V in Rome, including artwork destined for Ribeira Palace and the famed Chapel of St. John the Baptist, destined for the Igreja de São Roque, in what is now known as the Weale Album.
In 1748, Pereira de Sampaio achieved what is considered as the high point of his career, the granting of the style Most Faithful Majesty, by Pope Benedict XIV to King John V.
Pereira de Sampaio died in February 1750, in Civitavecchia, of an asthma attack, while preparing for an expedition back to Lisbon with works of art destined for the Patriarchal Basilica in Lisbon. He is buried in Sant'Antonio dei Portoghesi with a funerary monument dedicated to him designed by Filippo Della Valle.