Léon: The Professional

Léon: The Professional, starring Jean Reno and Natalie Portman, follows a calculating professional hit man (Reno), with no family and no friends. However, he has casually befriended Mathilda (Portman, in her stellar debut), a 12 year-old neighbor whose entire family, including her adored four-year-old brother, is wiped out by crooked DEA agents.

The girl pleads with Leon to teach her how to be a "cleaner" and avenge her little brother's death. However, once she learns a few skills, Mathilda saunters into the DEA offices with the sole intention of killing the psychotic agent (Gary Oldman) who actually masterminded the executions. But her intended victim turns the tables on her, and Leon must rescue her.