There are several common shapes of flag banners, including feather flags, teardrop flags, rectangle flags, and bowhead flags. Feather flags are typically tall and thin with a curved top, while teardrop flags have a similar shape but with a more rounded bottom. Rectangle flags are rectangular, and blade flags are similar to feather flags but with a straight top. Each shape has its unique advantages, and the choice of which one to use will depend on your specific needs.