A Fighter Fly (also spelled Fighterfly) is a grinning, moth-like pest that first appeared in the sewers of the original Mario Bros. arcade game. They are characterized by their ability to hop – an ability that allows them to cause trouble for Mario and Luigi.
 Mario Bros.
In Mario Bros., Fighter Flies are one of the myriad of pests that emerge from pipes to attack Mario and Luigi. They first appear in Stage Six. After a Fighter Fly emerges, it hops across the stage's platforms. As such, Mario has to precisely time his Jump when the Fighter Fly is on the ground to flip the creature over. If airborne, a Fighter Fly cannot be flipped over - not even if Mario uses the POW Block. Once flipped over, Mario has to run into the insect to clear it off the stage.
 Super Mario Land
In Super Mario Land, Fighter Flies are simply named Flies and are seen in the Birabuto Kingdom of Sarasaland. In this game, they hop towards Mario, just like in Mario Bros.. Kumos from the Easton Kingdom attack in the same manner as Fighter Flies. They can simply be jumped on or be shot with a superball to be defeated. Flies award Mario with 400 points when he defeats them. They are only found in the first stage, World 1-1.
 Mario & Luigi: Superstar Saga
In this game, they make a surprise reappearance. They live in Stardust Fields, the border between the Mushroom Kingdom and the Beanbean Kingdom. To attack, a Fighter Fly hops towards Mario or Luigi and tries to bump into the plumber. The heroes can jump to avoid the attack.
 Super Mario 3D World
Fighter Flies appear in Luigi Bros.; an additional game featured in Super Mario 3D World. Like the other enemies in Luigi Bros., Fighter Flies behave in the same way as Mario Bros., which this game is based on.
 Names in Other Languages
Super Mario Land
Mario & Luigi: Superstar Saga