BioShock’s Little Sister is one of the creepiest characters I’ve seen in video games — I think it’s partially because she’s a kid. That said, cosplayer Amiko, also known as Amiko-chan, still makes her look scary even though she’s an adult. She made the costume a few years ago because she loved the game and crafted the dress and syringe. She said the overall costume was pretty simple but it didn’t need to be overly fancy to get amazing images.
If you’re feeling inspired to make a Little Sister costume, we have a guide for 3D printing the syringe: