Count Francesco Algarotti (11 December 1712 - 3 May 1764) was an Italian philosopher and art critic.
He was born in Venice. He studied at Rome and Bologna, and at the age of twenty went to Paris, where he became friendly with Voltaire and produced his Neutonianismo per le dame, a work on optics. Voltaire called him his "cher cygne de Padoue" ("dear swan of Padua"). Returning from a journey to Russia, he met Frederick the Great who made him a count of Prussia in 1740 and court chamberlain in 1747; they are said to have been lovers. Augustus III of Poland also honoured him with the title of councillor. In 1754, after seven years' residence partly in Berlin and partly in Dresden, he returned to Italy, living at Venice and then at Pisa, where he died. Frederick the Great erected to his memory a monument on the Campo Santo at Pisa. He was a man of wide knowledge, a connoisseur in art and music, and the friend of most of the leading authors of his time.
His chief work on art is the Saggi sopra le belle arti ("Essays on the Fine Arts"). Among his other works were Poems, Travels in Russia, Essay on Painting, and Correspondence.