Leon (1994)

Professional assassin Leon reluctantly takes care of 12-year-old Mathilda and teaches her his trade.

After his small but memorable role in La Femme Nikita as "the cleaner", Jean Reno had this movie designed around him by the director Luc Besson. It feels very European despite being set in New York and features many quirks of which most assassin films fail to include in order to lift them above all the others in the action genre. Instead, Leon is primarily a love story, focusing on the relationship blossoming between the naive, childlike Leon, and the savvy, grown up Mathilda. Because of the evident and illegal age gap, various scenes were even cut from the English version as they gave the impression that the couple were getting a bit too close for the censors liking, however in context with the characters there is nothing offensive about their suggested affections.

Gary Oldman hams it up to the maximum as the drug crazed bad guy, delivering another awesome performance in every scene and relishing each line of dialogue.
I fucking love this film, not least because it introduced the world to Nathalie Portman.