Which film listed is about a hitman who takes an orphan girl under his wing to become his protégée?

The 1994 film where a hit man that takes an orphan girl under his wing is called "Leon: The Professional" aka "The Professional" in USA. Jean Reno, Gary Oldman, Natalie Portman, and Danny Aiello star in "The Professional". This film is a go-for-broke thriller about a professional assassin whose work becomes dangerously personal.

Calling himself a 'cleaner', the mysterious Leon is New York City's top hitman. When his next door neighbors are murdered, Leon becomes the unwilling guardian of the dead family's sole survivor. Twelve year old Mathilda is the one. But, she just doesn't want protection, she wants revenge. Training her in his deadly business, Leon helps Mathilda get even with the psychotic guy who killed of her family.

"The Professional" is full of action, suspense, and surprises. It is an English language French action crime film that was written and directed by Luc Besson. It was produced by Patrice Ledoux and distributed by Gaumont Buena Vista International Corporation. After it release, the film received favorable reviews from most movie critics. "The Professional" was a commercial success; it grossed over $45 million dollars worldwide on a budget of just under $16 million dollars.