Silver Shamrock

Silver Shamrock is an evil organization that acts as one of the primary antagonists of Halloween III: The Season of The Witch - where it developed a cult following due to very successful marketting in the form a near-omnipresent advert and theme tune that appeared throughout the movie.

The goal of Silver Shamrock was the sell seemingly harmless Halloween masks to children that were actually installed with deadly lasers that would kill the children after being activated (in addition the masks were cursed to unleash a swarm of insects which would in turn kill anyone near the child who was killed).