Any problem can be solved by the application of a fist to the right guy's face.
This is the Action Hero's primary operating procedure.
An Action Hero is a form of protagonist who primarily uses their fighting skills to achieve their goals in a story. If there's something in their way, their main response is to beat it up. This could be because they don't have the patience or skills for any other method, or because they just don't have the time. But then again, maybe they actually do try other methods first but it always seems to turn out that Violence Really Is the Answer.
Because their main trials in the story end up being direct conflict, they are always some form of badass or Action Survivor, and it doesn't matter how many battles they have to fight or things they have to blow up, they won't give up. They may use physical combat, brute strength, weaponry or even Mecha to lay the beat-down on their enemies, but they'll always deliver it personally — no standing on the sidelines for this hero. When they do come up against a problem they can't fix with his fists, they might attempt to use their tried and true methods regardless, resulting in a Nice Job Breaking It, Hero situation, or if they're really lucky, Cutting the Knot. For some things though, they may have to rely on another team member.
Also, the Action Hero's storylines are limited to the sort of thing where punching someone in the face actually would solve the problem, unless they're explicitly being taught An Aesop about how "you can't solve all your issues with violence", or they're being set up to fail. Relatedly, the climax to an Action Hero's story almost always culminates in a Final Battle of some sort. While the Action Hero often follows the trope Dumb Is Good, resulting in an Idiot Hero, that need not always be the case. If the Action Hero routinely uses other methods, such as cunning or science, then they may overlap with the Guile Hero or Science Hero roles.
It should also be noted that just having a fight scene does not make one an Action Hero! A character must use combat in ways that relate directly to the main driving force of the story, not simply in the occasional Bar Brawl, or even for protection. If the Hero's main goal is to save their little sibling from danger, then they have to kick somebody's ass to do it. The Hero can do all the unrelated fighting on the side that they want, but if they don't use it to accomplish their primary goal then it does not make them an Action Hero. Likewise, a character can be a badass, or show skill in combat, without actually being an Action Hero. If a character never seems to be working towards anything in particular, coming up against problems or facing trials, and generally acting as a Satellite Character, then this trope cannot apply to them.
This trope is not gender specific and can apply to both males and females. A female Action Hero is an Action Heroine while the male Action Hero is, well, you know, Action Hero. Please be aware that an Action Girl is not the Distaff Counterpart to Action Hero, but a female combatant, and Action Hero not being a Spear Counterpart to Action Girl. When two Action Heroes team up, they may form an Action Duo.
A Super-Trope to Action Genre Hero Guy, Action Girl, Action Pet, Hollywood Action Hero, Nerd Action Hero. See also Minored In Ass Kicking.
This trope can overlap with Guile Hero (a Hero who primarily uses cunning to accomplish his goals) and/or Science Hero (who primarily uses science to do so).