Mithridates, King of Pontos (Turkey), approx. 114-63 B.C.
This king lived in fear of being poisoned, so he constantly experimented on himself with antidotes. He created an antidote called Mithridatum, and kept the recipe a secret until Romans invaded his kingdom and stole the recipe. Ironically enough, when hearing of the invasion, Mithridates tried to kill himself… using poison. That (SHOCKER) didn’t work, so he got someone to stab him instead.