Slang term to describe only the worst kind of criminal. Ferocious, unrelenting, hardcore, psychotic crazy person. Feared by even the most notorious of mobs and mafiosos, a Myrtle, often serves as a type of hired gun to "take out the trash" when all others have failed, but usually works for free simply for "the love of the kill". In some countries a myrtle is regarded as a myth due to it's ability to stay "under the radar" leaving no trace of it's devoured victims. No Myrtle has ever been convicted of a crime due to the tendancy of witnesses to disappear.
Pissing off a Myrtle is a deathwish.
Mob Boss 1: Hey Joey! The iceman screwed up the job!
Joey: Get me the Myrtle....