An Action Girl is a female badass who is tough and kicks butt. Damsel in Distress? Not her (mostly). She's featured in far more than the Designated Girl Fight. She faces dangerous foes and deadly obstacles, and she wins. She's a fairly common character in the Action Genre.
For the longest time in many cultures, Double Standards in both fiction and Real Life meant that when it came to action and fighting, guys definitely outnumbered girls. Men Act, Women Are was the rule of thumb, which led to the Action Girl being a subversion of what was acceptable. As society has marched on, this view has faded in some media, leading to stories where Action Girls become the norm rather than the exception, such as stories set in a World of Badass, and especially a World of Action Girls.
The broad Action Girl concept can take many forms. Faux Action Girl is a case of presenting a character as this, only for them not to live up to the standards of this trope. Dark Action Girl is the villainous variety, and Affirmative Action Girl is a cast addition intended to balance out gender ratios that typically also falls under this trope. Less action-y versions include You Go, Girl! and Plucky Girl.
This is somewhat of a Cyclic Trope, with Action Girls often having surges in popularity in the 1940s, 1970s, 1990s and 2010s, probably not coincidentally times when the women's movement increased in prominence. Action Girls are nigh-omnipresent in modern action films, especially as the love interest or sister of a male Action Hero. Of course, this doesn't mean lesbian Action Girls don't exist.
See below for even more sub-tropes and other variants.
For advice on how to write these types of characters, see Write an Action Girl.
