Leon the Professional (1994)
If you want a job done well, hire a professional. That's the tagline for this rather touching -- if one can call a film about assassins that -- film about a professional assassin who teaches his 12-year old neighbour the tricks of the trade after her family is killed by an errant cop (Gary Oldman).
Directed by Luc Besson, the film won numerous awards and stars French actor Jean Reno as the assassin and Natalie Portman as his student.
The actress was originally turned down for the role on the grounds that she was too young, but came back with a brilliant audition that clinched it.
Also read: Hollywood's bow-wow brigade