Rider: Alexander in Babylon by Charles le Brun
Archer: The Statue of Gilgamesh
Lancer: The Tree of Love
Caster: The Execution of Gilles de Rais
Assassin: Artistic Rendition of Hassan-i-Sabbah
Berserker: Idylls of the King by Alfred Tennyson
Saber: Battle of Camlann by Arthur Rackham
This alone demonstrates the superior sophistication of Fate/Zero over Fate/Stay Night. I love all the servants in F/Z. The same cannot be said for F/SN.