Undodog

“Undodog will help you correct a minor mistake by cancelling your last action. You will quickly find that this hound is a great friend.”
—Mario Paint US Instruction Manual, page 6

Sprites of Undodog (left) with his icon (right)

Undodog is a dog who appears as a helpful character in Mario Paint, selectable as an icon in the bottom toolbox in the Art and Music modes. His appearance is that of a tan dog with a thin black box around his neck, like a collar, probably representing the outline of his icon. His name is a pun on the word "underdog", is a portmanteau of the words "undo" and "dog", and, as his name states, he helps the player undo the last action. He will also dance and jump around at the bottom of the screen when selected. If the player turns the game's music off and leaves it silent, Undodog will sometimes sneeze loudly. According to the instruction manual for the game, this is because of his allergies. He reappears in Super Mario Maker, with the same function as his original appearance: reverting the player's last edit.

Undodog makes cameo appearances in the WarioWare: Touched! microgame, Mario Paint, and his icon can also be seen in the WarioWare: D.I.Y. microgame for Mario Paint.