Johann Matthias Reichsgraf von der Schulenburg was a German aristocrat and general of Brandenburg-Prussian background who served in the Saxon and Venetian armies in the early 18th century and found a second career in retirement in Venice, as a grand collector and patron. His sister was Melusine von der Schulenburg, Duchess of Kendal. His father was :de:Gustav Adolf von der Schulenburg|Gustavus Adolphus, Baron von der Schulenburg.
In his retirement in Venice from 1718, the Reichsgraf von der Schulenburg proved a remarkable collector of art while residing in the Palazzo Loredan on the Grand Canal of Venice. The Reichsgraf began as a serious collector in 1724, at the age of sixty-three, with a purchase of eighty-eight paintings and a bas-relief by Pierre Puget from a Venetian picture-dealer, Santi Rota, who had obtained them from the collection of Ferdinando Carlo Gonzaga, the last ruler of the Duchy of Mantua, deposed by Habsburg Austrian empire; Gonzaga's works of art included works by Raphael, Correggio, Giorgione, Giulio Romano, and Castiglione. In addition Schulenburg had access to many royal families, including the Hanoverians, Bourbons, and Habsburgs; and served them as an intermediary and bon-vivant host in the Venetian republic. His portrait was painted by Bartolomeo Nazari, Giuseppe Nogari, Giacomo Ceruti, Gian Antonio Guardi, Francesco Simonini, and Piazzetta, and he was sculpted by Antonio Corradini and Gian Maria Morlaiter. Schulenburg supported Gian Antonio Guardi with a monthly salary, 1730–36, and on a commission basis thereafter. In general, Guardi worked at making portraits of foreign aristocracy and royalty to impressively adorn the walls at Ca' Loredan, and at copying masterpieces of the Venetian past including works of Paolo Veronese and Tintoretto. Francesco Simonini was commissioned to produce a series of paintings commemorating Schulenburg's battles. Canaletto painted a view of Corfu, the site of his victories.
He also employed Giambattista Pittoni, 1733–38, for history paintings, and as advisor and restorer. Finally, Giovanni Battista Piazzetta had a close relationship with the Marshal, both as painter as an agent for buying both Flemish and genre paintings, two types of works popular with Schulenburg; Piazzetta made an inventory of the collection in 1739. Schulenburg's paintings were mainly Italian works of the sixteenth and seventeenth centuries, with some Flemish and Dutch paintings. He owned six paintings by Giacomo Ceruti. He owned vedute by Michele Marieschi, Luca Carlevaris, Giovanni Battista Cimaroli, Antonio Joli, Marco Ricci, and Francesco Zuccarelli; thus he overlapped to some degree with the collecting of the contemporary British ambassador, Joseph Smith. Many of his works were transferred to his estates in Germany, like Emden, Hehlen and Beetzendorf. Schulenburg did not have children and, though he willed his collection en bloc to his nephew Count Adolf Friedrich von der Schulenburg-Beetzendorf with the stipulation that they be kept together, in the Palais Schulenburg in Berlin, his will was not honoured, and after his death his collection was dispersed. A distinguished customer was Frederick II of Prussia. A group of 150 pieces were sold at auction in London in April 1775.