|Applies to||Mario, Luigi, Yoshi|
|Item needed||Hone; Fishbone's "Bone Ray"|
|First appearance||Super Mario-kun volume 1 (1991)|
|Latest appearance||Super Mario-kun volume 6 (1993)|
The first occasion in which this form is shown is the last chapter of volume 1, as one of the hypothetical future transformations of the Super Mario franchise. Mario can transform into a skeleton for three minutes after collecting a Hone, but it has no known advantages or powers.
In volume 2, a Fishbone attacks the heroes by shooting a "Bone Ray", turning Luigi and Yoshi into skeletons. Before Mario can be hit, however, a Super Star grants him invincibility, and he defeats the enemy. Meanwhile, Luigi and Yoshi ask how they will turn back to normal.
- A skeletal Mario would later appear in the games in Super Mario Galaxy as a death animation from electric attacks, and as a costume in Super Mario Odyssey.
|Ball Yoshi • Balloon Yoshi • Bitsize Candy (form) • Biyon Yoshi • Blimp Yoshi • Bloway Candy (form) • Boat Yoshi • Bobsled Yoshi • Bowlo Candy (form) • Bowser Candy (form) • Bulb Yoshi • Bullet Candy (form) • Car Yoshi • Cashzap Candy (form) • Dash Yoshi • Duelo Candy (form) • Ghost • Goomba Yoshi • Hae Yoshi • Helicopter Yoshi • Hoppycat Yoshi • Hot-Air Balloon Yoshi • Hyper Breath • Jackhammer Yoshi • Kinoko Block Yoshi • Mega Yoshi • Mermaid Yoshi • Metal Yoshi • Mine-Cart Yoshi • Mole Tank • Mole Yoshi • Moto Yoshi • Mushroom* • Plane* • Puffy Lift Yoshi • Shield Yoshi • Ship Yoshi • Skeleton Yoshi • Ski Yoshi • Sky Pop Yoshi • Snowball Yoshi • Spark Yoshi • Spike-Ball Yoshi • Springo Candy (form) • Star Yoshi • Submarine Yoshi • Super Happy • Super Yoshi • Thwomp Candy (form) • Train • Tree* • Umbrella Yoshi • Vampire Candy (form) • Weeglee Candy (form) • Winged Yoshi • Wubba Yoshi • Yoshi Kart|
|* Unused forms|