Marcello Bacciarelli (16 February 1731 – 5 January 1818) was a Polish-Italian painter of the late-baroque and Neoclassic periods.

He was born in Rome, and studied there under Marco Benefial. In 1750 he was called to Dresden, Saxony, where he was employed by Elected King Augustus III of Poland; after whose death he went to Vienna, and thence to Warsaw. There he met and worked by the side of another Italian painter in Dresden, Vienna and Warsaw, Bernardo Bellotto. He was the Director there of the newly set up Academy of Arts of Warsaw.

He painted a set of the Polish kings, from Boleslaus Chrobry forwards. That of Stanislaus II, Stanisław August Poniatowski has been engraved by A. de Marcenay de Ghuy, Küstner, and A. Fogg. He also made a portrait of Izabela Lubomirska in her wedding gown, that she commissioned years later after her marriage. Bacciarelli also painted scenes from the history of Poland. He died in Warsaw.

A number of his paintings were painted for King Stanisław August Poniatowski of Poland and are in the Royal Castle in Warsaw. These include:

• Strength, Reason, Belief, and Justice, in the Old Audience Chamber
• The Flourishing of the Arts, Sciences, Agriculture, and Trade on the ceiling of the Old Audience Chamber
• Rebecca and Eleazar in the King's Bedroom
• Esther and Ahasuerus in the King's Bedroom

During Bacciarelli's early years in Warsaw, the young Alexander Kucharsky began to train as a painter in his studio. Another notable pupil of Bacciarelli's was Kazimierz Wojniakowski.