My Avatar Editor is a free online site where you can create and edit avatars. Gender, height, size, hair and eye color, along with other physical characteristics can be chosen. Once an avatar is created, it can be exported as a .png file without the background.
My district uses Comic Life, and by combining this with Comic Life, students could create historical scenes. Normally, you are only able to drag one picture into a frame in Comic Life, but by saving the Avatar without a background, and using the "command" key while dragging the image onto a background image, a scene like above can be created.