Axe

The Axe (or ax ) is an object found in the Mario franchise of games, often appearing in castle levels.

Super Mario Bros.
Axes first appear in Super Mario Bros., where they appear in castle levels, where the player can defeat Bowser or his duplicates by touching the Axe, which cuts the support of the bridge Bowser is standing on and sends him falling into the lava below. If the player does not have a Fire Flower, using the Axe is the only way that the player can defeat Bowser.

Super Mario Bros.: The Lost Levels
Axes reappear in Super Mario Bros.: The Lost Levels, where they function the same as they did in Super Mario Bros.

Super Mario Advance 4: Super Mario Bros. 3
An axe reappears in Super Mario Advance 4: Super Mario Bros. 3, in the World-e level Classic World 1-4, having the same function as they did in Super Mario Bros.

New Super Mario Bros. U
In New Super Mario Bros. U the axe reappears, serving the same purpose as it did in Super Mario Bros., although it is activated by a ! Switch, like in the New Super Mario Bros. games, where the axe is replaced by a either a ! Switch or a Skull Switch, although in those games the axe is absent.

Super Mario Maker / Super Mario Maker for Nintendo 3DS
The axe reappears in Super Mario Maker and Super Mario Maker for Nintendo 3DS, as the goal for Castle-style courses, with its appearance being different depending on the game style, with axes sharing the same function as seen in Super Mario Bros., though its appearance in the Super Mario Bros. style has been changed to make it taller and wider.

Super Mario Run
The axe reappears in Super Mario Run, retaining its look and function from the New Super Mario Bros. U style in Super Mario Maker.

Super Mario Odyssey
Following the October 17, 2018 update for Super Mario Odyssey, a single-bladed axe appears as Cappy's form for the "Zombie Headwear" purchasable clothing from Crazy Cap.

Mario & Luigi: Superstar Saga
The axe reappears in Mario & Luigi: Superstar Saga, where it cameos alongside a paper duplicate of Bowser in a Super Mario Bros.-reminiscent section of Bowser's Castle.

Mario Hoops 3-on-3
The axe reappears in Mario Hoops 3-on-3, where on the Bowser's Castle court the basketball hoop's pole is a giant Axe.

Super Smash Bros. Ultimate
Although the axe does not appear as an item in Super Smash Bros. Ultimate, it being key to defeating Bowser in the older games is given an indirect reference with one of Simon Belmont's screencaps, where he is seen about to use his Axe special attack on Bowser.