The earliest known depiction of the crucifixion of Jesus, the Alexamenos Graffito, is believed to date back to the third century CE. The caricature carving mocks Christianity and the crucifixion by giving Jesus an ass's head. The inscription reads: "Alexamenos - worship your God !".
The carving was found on a stone in a guard room on Palatine Hill in Rome near the Circus Maximus in 1857, and is now in the Palatine Antiquarium. Some date it to the first century CE. Others traditionally date the graffito to the third century, when Tertullian wrote of accusations that Christians worshipped an ass's head: "Somniatis caput asininum esse Deum nostrum" (Apol., xvi; Ad Nat., I, ii)... meaning, "You talk nonsense by suggesting that our god is the head of an ass".
(carving, Alexamenos Graffito, c. 3rd century)