Barrelhoppers (known as Barrel Impostors) are rare robotic enemies, they disguise themselves as a barrel who are invented by Elder Bowser Jr. in the future or just Bowser in the Present
They look like Blockhoppers except they are different : They disguise themselfs as a barrel instead of blocks, they have red eyes, they have SMW-Blue Feets
It would attack Mario by jumping when Mario looks away, it will follow the character, If mario looks back at it, it will hide in it's barrel
It first appears as a rare enemie in this game, It only appears in one level named "Barrel Library", it can attack mario by rolling into him when Mario looks at it too long, Mario can carry it's body when it's hiding and throw it, some of them can roll while some cannot but break, there is a giant Barrelhopper mini-boss named Marrelhopper.
- It bares a resemblance to any barrel kremlings from DK Series
- In Super Mario Bros.: The Popstar Crossover, their feets are colored brown instead of blue.