Piranha Plants are recurring enemies throughout the Mario series. They first appeared in the original Super Mario Bros. games, were they would come out of certain pipes. They then appeared in Super Mario Bros. 3, where they looked more like their modern design. They appear in Yoshi, Super Mario World 2: Yoshi's Island, Yoshi's Story, and Yoshi's Island DS.

Piranha Plants are similar in appearence to the venus fly trap. They have teeth to chomp with and have a red head with white spots. If Yoshi gets too close to a Piranha Plant, it will swallow him, and Baby Mario will float off in a bubble. After a few seconds, the Piranha Plant will spit him out and Yoshi will have to catch Baby Mario. Another variety is a green Piranha Plant. It doesn't eat Yoshi, but instead shoots spikey cactus-like balls at him. It must be hit three times before dying, unlike the regular Piranha Plant, which dies after one shot. It turns orange then red then dies.

Piranha Fish are also seen in Naval Piranha's fortress. They behave similarly to regular Piranha Plants. However, they do not die if you hit them with an egg.

Notable Piranha Plants are Petey Piranha and Naval Piranha.