Costumes based on movies and video games are pretty common, especially if those video games are turned into movies. Quality of such productions aside, the characters themselves can be pretty popular. While barely related to the video games, their characters are well known in their own right.
The main and literal poster character for the movies, Alice has worn a variety of outfits and equipment, depending on the movie in question. This gives a fair bit of versatility in costuming. The easiest costume is the white slip dress, shorts, and boots. They get more involved from there, but usually include pants, a black shirt, and some form of vest or overalls. In "Resident Evil: Apocalypse" she is wearing a brown mesh vest and black leather pants or shorts.
When it comes to equipment, she usually carries either a pair of handguns, double barrel shotguns, or submachine guns. She may have an assault rifle instead. Toy versions of most of those are easy enough to find, but make sure they're brightly colored so people know their fake.
Thanks to how many movies have been released, you have a bit of creativity with which costume you choose. In a pinch, a tank top, shorts, vest, and some toy guns will do the job. it's a bit generic, sure, but it will work, though won't be very comfortable in colder weather.
Ada was first introduced in "Resident Evil: Apocalypses" and is a prominent character in the movies and video games. The costume is pretty easy to find/make outfit. Ada's main outfit is a red slip backless dress over a black tank top or bra. The dress has golden butterflies on the left side, along with fishnet socks. She belts her handgun holster to her right leg. While not ideal in cold weather, it would be nice for a party.
Ada's costume is both easy and difficult, because it's so specific. Fortunately, that means finding it on sites dedicated to cosplay and the like, or finding something similar and making it work, shouldn't be too difficult. Just make sure to take time into account if having the costume made.
Also note her weapon tends to change. She uses both a conventional handgun and a custom, sci-fi contraption depending on the movie. Said custom model might need some tinkering to look right. She's used a Thompson submachine gun as well, though that was mostly in the games.
While finding the right clothes might take some time, it'll be worth it to make a more authentic costume for whatever occasion you desire one. Alice's costume options are a lot more varied, though Ada's has a formal and seductive flair that would lend it well to costume parties.
Zombie Hoards (Bad Guys)
Who doesn't like dead people? Well, at least when it comes to Halloween parties. in the movie, "Resident Evil Apocalypse" there are plenty of zombies for our hero to fight. The number of zombie movies and TV shows is constantly growing. The Walking Dead, Z Nation, Dawn of the Dead and of course Resident Evil. The best part is that these costumes are not all the same, so you can actually choose one that you think is scary or cool.
Keep in mind there is a thin line between funny and scary mask, so be careful in your choice. Zombie masks are great because you don't have to think too much about the outfit; for example, you can find some old clothes or make your regular ones look dirty or worn. Of course, don't forget to walk slow or at least act weird.
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