First appearance: Leprechaun (1993)
In 1983 a man captures a Leprechaun and brings the pot of gold home to his wife in the U.S. Unfortunately for him the Leprechaun isn't going to let the gold go so easily and has stowed away in the man's luggage. After killing the man's wife the man once again defeats the Leprechaun by showing it a four-leaf clover (a leprechaun's only weakness) and imprisoning in a crate. Just as he's about to set fire to the crate the man has a heart-attack and dies.
Ten years later a family rents the house containing the Lepre-crate. The Leprechaun tricks a mentally-challenged man in to freeing him and mayhem ensues.
This franchise includes an adventure in space (Leprechaun 4: In Space) and two set in "The Hood" (Leprechaun 5: In the Hood and Leprechaun 6: Back 2 tha Hood). Why? I don't know.