Mithridates of Pontus

Mithridates of Pontus or Mithridates VI Eupator fought against the forces of Sulla, Lucullus, and Pompey during the Mithridatic Wars until Pompey defeated him. When Mithridates learned his son Pharnaces had turned against him Mithridates tried to commit suicide, but is said to have had trouble because he had built up an immunity to poisons. A friend helped him -- with a sword.