No Good Fly is an enemy that appears in Earthbound. They are first encountered by Ness and Paula in Southern Threed and the Threed Cemetery during the zombie infestation. These enemies are small and bee-like, with antennae and four wings. Their sprite looks similar to Buzz Buzz since they are flying insectoids.

These flies have two in-battle actions. The first being its standard attack, which can deal low to minimum damage. The last action is, "saying something nasty" which lowers the guts of one member of Ness' party by a minimum rate. This enemy has a relatively low HP and defense, since they cause minimal harm. This enemy is vulnerable to Paula's PSI Fire, PSI Freeze, Ness' Paralysis, and the Insecticide Spray. Once this enemy is defeated, it gives 415 EXP, $26, and a Boiled Egg 4/128 of the time.

No Good Flies can be grouped with other No Good Flies, Putrid Moldymen, Smelly Ghosts, and Zombie Dogs. Their in-battle theme is, "Battle Against a Mobile Opponent."