Vincenzo Brenna (August 20, 1747 – May 17, 1820) was an Italian architect and painter who was the house architect of Paul I of Russia. Brenna was hired by Paul and his spouse Maria Fyodorovna as interior decorator in 1781 and by the end of 1780s became the couple's leading architect. Brenna worked on Pavlovsk Palace and Gatchina palaces, rebuilt Saint Isaac's Cathedral, and most notably created Saint Michael's Castle in Saint Petersburg. Most of his architectural works were created concurrently during Paul's brief reign (November 1796 – March 1801). Soon after Paul was murdered in a palace coup Brenna, renowned for fraud and embezzlement barely tolerated by his late patron, retired and left Russia for an uneventful life in Saxony.

Brenna never reached the level of his better known contemporaries Giacomo Quarenghi, Charles Cameron and Vasili Bazhenov and was soon surpassed by his own trainee Carlo Rossi. Nevertheless, historians Igor Grabar, Nikolay Lanceray and Dmitry Shvidkovsky praised him for sincere and unrestricted naturalism of his graphic work and considered him to be the watershed between the Age of Enlightenment and Romanticism in Russian architecture.

Brenna belonged to an old Ticino family that had split into two branches, stonemasons (Brenno) and painters (Brenni) not later than the last quarter of the 17th century. Stonemasons and marbling experts Karl Antonio and Francesco Brenno worked in the 1680s in Salzburg. Karl Enrico Brenno (Brennus) carved elaborate tombs in Denmark and Hamburg, but was better known for his marbling artwork at Fredensborg, Christiansborg and Klausholm palaces. Giovanni Battista Brenno, stucco expert, worked in Bavaria. The other branch produced three brothers Brenni (born in the 1730s), fresco painters. Vincenzo Brenna, son of Francesco, was born in 1747 in Florence (19th-century sources list him as a native of Rome, perhaps due to his signature Del cavalier Brenna Romano). It is not clear whether Vincenzo Brenna belonged to Brenno or Brenni branch.

Since 1767 Brenna studied crafts in the Roman workshop of Stefano Pozzi together with his better known contemporary Giacomo Quarenghi. Quarenghi, who leaned to painting, converted to architecture under Brenna's influence and later even gave Brenna, who was three years younger than Quarenghi the credit for being "my first teacher in architecture". Brenna himself did not have luck in tangible architecture; instead, commissioned by Lodovico Mirri under auspices of Pope Clement XIII, he surveyed the relics of Rome together with Franciszek Smuglewicz. Their drawings, engraved by Marco Carloni, were published in the late 1770s as Vestigia delle Terme di Tito. Another set of Brenna's drawings, created not later than 1781 and engraved by Giovanni Cassini, was published in three folios (380 sheets) from 1781 to 1788. It is not known if Brenna had a chance to meet Charles Cameron, who also surveyed Rome in the 1770s, prior to Brenna's arrival in Russia. Brenna eventually "arrived at a more theatric conception of Antiquity than the Scot," and created architecture radically different from Cameron's.

Back in Italy Brenna met Stanisław Kostka Potocki, a well-educated and rich amateur in need of professional artists. Brenna followed Potocki to Poland where he prepared two drafts of a church in Ujazdow. He received commissions to decorate Potocki's palace in Natolin, for which "compensated" himself from his patron's art collection. The two parted in a bitter conflict; "Brenna's thievery, double-dealing and desertion of his benefactor Potocki for the future czar seem the unkindest cuts of all". According to Lanceray, Brenna also painted frescoes in Warsaw for the king Stanisław August Poniatowski.

In the end of 1781 Russian heir apparent Paul (reigned as Paul I of Russia) and his spouse Maria, travelling on a Grand Tour of Europe under the thin guise of Comte du Nord, noticed Brenna's work in Warsaw. Paul, aware that Charles Cameron needed interior decorators for his Pavlovsk palace, offered Brenna employment in Pavlovsk. Brenna and his assistant Franz Labensky were formally hired by Maria for a starting annual salary of 200 roubles. Most recent sources (Shvidkovsky) date Brenna's arrival in Russia as the beginning of 1784; Lanceray described Brenna's Russian drafts dated 1783.

Meanwhile, when Paul and Maria were in Europe, Cameron began displaying signs of aversion to their interference with his work. Court intermediaries suppressed the conflict for a while, but by 1785 Maria herself grew tired of Cameron's alleged inefficiency and warned him, through Count Kuchelbecker, that he will not see any new commissions. Cameron's influence faded, influence of his assistants, including Brenna, rose, powered in part by the Italians' assertive, self-confident behaviour. Aspiring Brenna was caught in the middle of "battle of the palaces", an expensive ideological contest between Catherine and Paul "hidden from the uninitiated but known to the court". Catherine made the first move, razing Bazhenov's gothic towers of Tsaritsyno Palace. Cameron, dismissed by Paul, was the second casualty. Paul suspected him of carrying out Catherine's orders: Cameron built for him "a markedly private world", not an imperial palace. Brenna, already Paul's trusted servant, was an ideal replacement. According to Lanceray, Paul used Brenna for visualizing his architectural fantasies as early as 1783–1785. Maria also favored Brenna; in 1787 she wrote that she was "fascinated by Brenna's return to work" inherited from Cameron.

By 1789 (Shvidkovsky: 1786) Brenna, finally, was awarded his first tangible architectural project, remodeling of Paul's study suite in Pavlovsk. In 1794 Brenna was rewarded with a lot of land near to Pavlovsk palace. Paul's trusted barber Count Ivan Kutaisov, another Pavlovsk landlord, became Brenna's first private customer; he commissioned a summer dacha in "medieval style". By this time Brenna earned 750 roubles p.a., but when Paul ascended to the throne in 1796, Brenna's salary reached 3,550 roubles.