Returning War Vet

A Stock Character of many B-grade action movies, video games, and even a few dramas. A character returns home from the military. May be related to Stranger in a Familiar Land if they have trouble adjusting to normal life again.

The staple of this trope is that the returning soldier will inevitably be called upon to put his career skills to good use. He might find his hometown overrun with crime bosses, monsters, ghosts, or whatnot depending on the genre of the story. But he will always be the one to save the day, as he's the only one who has the training.

When done well, his military history will not be his only definable characteristic. When done poorly, he's little more than a mobile set of fatigues.

Examples of Returning War Vet include:

Comics

The Punisher

Film

In 2004's remake of Walking Tall, Dwayne "The Rock" Johnson plays a returning soldier who must clean up his small town after drug dealers and criminals overrun it.
Tom Cruise plays a returning vet in Cocktail, though this is one of the rare examples where what he learned in the military proved of no use to him later on.
Rambo in First Blood would fit this, though it wasn't his home town; he was just passing through and trying to look up one of his war buddies.
Parodied in I'm Gonna Git You Sucka, where Jack Spade was an Army vet...but his only experience was as an office clerk.
The most triumphant example, metaphorically speaking, would be Travis Bickle from Taxi Driver. In terms of Vietnam causing his total alienation from normal society.
Coming Home
The Deer Hunter
Michael Corleone in The Godfather comes back from World War II as a decorated Marine.
Tom Cruise is a paraplegic Vietnam veteran in Born On the Fourth of July.

Literature

The Executioner
Played with in Beyond the Moons by David Cook. Teldin Moore is a returned war veteran, all right. But what his career taught him is that for some people war isn't about heroic charges but mostly about burying the corpses, skinning mules and so on. Though at least he traveled far (on his legs) and has rather broad experience—for his world, anyway. Not that he got to live in it much longer.
Dr. Watson of the Sherlock Holmes stories served as a British Army medic in Afghanistan. He meets and begins working with Holmes almost immediately upon his return to England.

Live Action TV

Jake Green returns to Jericho after serving in the army. His training and skill with a gun are made into plot points throughout the series, and likely the reason why so many people look to him for safety.
Took up quite a few episodes in Band of Brothers.
In the backstory of Sons of Anarchy, the founding members of the club were returning Vietnam War vets. While it was not their original intention, their army training comes in useful when they become involved in gun running and engage in a bloody turf war with an rival gang.

Video Games

In Silent Hill Homecoming, Alex Shepherd comes back from overseas with the Special Forces only to find his father and brother are missing and he's being haunted by constructs from the titular town.
I think Bill from Left 4 Dead qualifies.
- Isn't he a Vietnam vet? He's been home for a while, if that's the case.
Cole Phelps in "L.A.Noire" is said to be a returning WWII vet who becomes a police officer in order to "right the wrongs committed during his time in the war."