Anton Raphael Mengs
Anton Raphael Mengs (1728 – 1779) was a Czech painter of German origin who worked mainly in Saxony and Spain. He was a precursor to Neoclassical movement. Other earliest Neoclassical painters were Joseph Marie Vien, Pompeo Batoni, Angelica Kauffmann, and Gavin Hamilton.
Mengs became court painter of Elector Augustus III, and later of the King of Spain Charles III. He wrote Reflections on Beauty and Taste in Painting (1762).
About 1755, he became a close friend of the German archaeologist and art critic J. J. Winckelmann, the author of the famous A History of Ancient Art (1764). Mengs came to share Winckelmann's enthusiasm for classical antiquity, and worked to establish the dominance of Neoclassical painting. 
Charles III of Spain.
Portrait of Johann Joahim Winckelmann.