Laocoon and his Sons (or Laocoon Group), Greek Hellenistic (most likely 42 -20 BC), Vatican Museums, Rome.
Laocoon warning about the Trojan Horse earned him the wrath Poseidon who sent serpents to attack him and his sons. Michelangelo was influenced by this work and the contortions of the body of Laocoon can be seen in many of his works, especially something like the Dying Slave.
Dying Slave
, 1513-16 by Michelangelo, Louvre, Paris.