Fake Bowser

Fake Bowsers (or Bowser Imposters) are various standard enemies that were transformed by Bowser's black magic into duplicates of himself. They first appeared in Super Mario Bros.

Super Mario Bros. / Super Mario Bros.: The Lost Levels
Mario has to fight seven Fake Bowsers (one in each castle) before he can reach Bowser's Castle and fight the real one. Defeating a Fake Bowser with five fireballs reveals that they are really just common enemies disguised as Bowser. The enemies and their abilities are:


 * World 1: Goomba - fire
 * World 2: Green Koopa Troopa - fire
 * World 3: Buzzy Beetle - fire
 * World 4: Spiny - fire
 * World 5: Lakitu - fire
 * World 6: Blooper - fire and hammer (NES) / hammer (SNES)
 * World 7: Hammer Bro - fire and hammer (NES) / hammer (SNES)

Super Mario Bros.: The Lost Levels additional worlds:
 * World A: Goomba - fire (FCD) / Red Koopa Troopa - hammer (SNES)
 * World B: Green Koopa Troopa - fire (FCD) / Green Cheep Cheep - hammer (SNES)
 * World C: Buzzy Beetle - fire (FCD) / Bullet Bill - hammer (SNES)
 * World D: Spiny - fire (FCD)

The "You VS. Boo" challenge of Super Mario Bros. Deluxe:
 * 1-4: Green Cheep Cheep
 * 2-4: Bullet Bill

Like Bowser, Blue Bowser in World D-4 is also a fake revealed to be a Spiny when defeated with fireballs, and breaths only fire. In Super Mario All-Stars, both of these fakes are replaced with Bowser and his double who, when defeated with fireballs, isn't turned into one of Bowser's minions.

Super Mario Advance 4: Super Mario Bros. 3
In Super Mario Advance 4: Super Mario Bros. 3, a Fake Bowser appears as a boss in the World-e level Classic World 1-4, where it plays a similar role to that played in Super Mario Bros., though it looks identical to the game's real Bowser. It is revealed that the Fake Bowser is a Goomba if it is defeated with fireballs.

Super Mario 3D Land
Fake Bowsers appear in the Nintendo 3DS game, Super Mario 3D Land. They have spiky raccoon tails, and they attack like they do in Super Mario Bros., breathing giant fireballs and jumping around the stage, though they do not throw hammers.

However, unlike in Super Mario Bros., only two Fake Bowsers appear: one in and the other in. They are also immune to projectiles. In order to defeat a Fake Bowser, Mario or Luigi has to press a switch at the end of bridge to make it collapse and send the Fake Bowser into the lava. After falling into the lava, Fake Bowsers bounce upwards and show their true forms (a Goomba in World 1, and a Magikoopa in World 5) with a Super Leaf beside them. The Prima guide refers to Fake Bowsers as Tail Bowsers.

Super Mario Run
In Super Mario Run, Fake Bowsers appear at the end of the Fortress levels in Worlds 1, 3 and 5. They are a Goomba, a green Koopa Troopa, and a Buzzy Beetle, respectively.

Mario & Luigi: Superstar Saga
A Fake Bowser makes a cameo appearance in Mario & Luigi: Superstar Saga. It is seen in a special area inside Bowser's Castle, which is a side-scrolling level imitating a Super Mario Bros. level, and appears at the end of that level. The Fake Bowser appears to be made of cardboard, and Mario must run underneath him and hit the axe to make him fall.

Mario & Luigi: Paper Jam
While a Fake Bowser never appears physically in Mario & Luigi: Paper Jam, one appears on a Battle Card, taking its design from Super Mario 3D Land.

Mario & Sonic at the Sochi 2014 Olympic Winter Games
A Fake Bowser appears as a boss in Mario & Sonic at the Sochi 2014 Olympic Winter Games, specifically in the Mario World version of Dream Figure Skating. The appearances of the stage and its boss are based off Super Mario 3D Land. He chases the team across a giant collapsing bridge, spitting fireballs at them. The team must hit four buttons at the same time to cause the Fake Bowser to fall into lava, where he turns into a Goomba and a Super Leaf.

Trivia

 * The World 3 and World C (original) Fake Bowsers are the only Buzzy Beetles that can be defeated by fireballs, and the World C (All-Stars) and "You VS. Boo" 2-4 (Deluxe) ones are the only Bullet Bills that can be defeated by fireballs.
 * Fake Bowser's Super Mario 3D Land artwork is in almost the exact same pose as Dry Bowser's artwork for Mario & Sonic at the Olympic Winter Games.