MITHRIDATES VI of Pontus

Mithridates VI (114- 63 B.C.) or Mithridates Eupator is the king who caused Rome so much trouble during the time of Sulla and Marius. Pontus had been awarded the title of friend of Rome, but because Mithridates kept making incursions on his neighbors, the friendship was strained. Pompey won his title "the Great" by defeating Mithridates.
Mithridatium
The name Mithridates is associated with the gradual building up of tolerance to poison by ingesting a little bit each day. Mithridates, who ruled from 120-63, is said to have ingested a little bit of all the known poisons (a universal antidote) each day starting early in his life. The term mithridatium is now used for an antidote to poison.