The Four-Panel Omake are comedic comics at the end of most volumes of the manga. They often delve deeper into the backgrounds of characters, such as the animal preferences of the Slicer Brothers.
- Hiromu Arakawa has often said that the bonuses are her favorite part of the manga.
- Although Fullmetal Alchemist: Brotherhood is a more faithful adaptation of the manga, each Omake is not adapted into 4-Koma Theater, the anime's version of omakes; instead the anime creates its own content.
- The characters in the omake are often drawn in a chibi style.