Roger the Potted Ghost is the boss of the level "The Potted Ghost's Castle" in the video game Super Mario World 2: Yoshi's Island.
Roger starts out as just an ordinary, lifeless flowerpot, but when the Blue Yoshi arrives in the boss room, Kamek uses his magic to transform it into a ghost.
To defeat Roger, the Blue Yoshi must push the flowerpot that he's in into the pit at the other end of the battle arena in the same manner as a regular flowerpot. However, the two green Shy Guys behind him will try to push him in the opposite direction, which will result in the death of the Yoshi if he's pushed too far, as there is also a pit at the opposite end of the arena. Roger can also lunge at the Blue Yoshi to push him back, and spit out blue flames that will force the Yoshi to stop pushing him and get out of the way in order to avoid getting hit. When he's pushed far enough, the green Shy Guys will fall into the pit behind him and will respawn, leaving the Yoshi free to push him the rest of the way without resistance.
Yoshi's Island DS
Roger the Potted Ghost makes a cameo appearance at beginning of the intro of Yoshi's Island DS, along with all of the other bosses fought in the original game.
In the original Super Nintendo version of the game, his name "Roger" is never revealed, and he is known simply as "The Potted Ghost", but it's revealed in the official guidebook. The Game Boy Advance remake of the game, Yoshi's Island: Super Mario Advance 3, also changes the the name of the level he appears in to "Roger the Potted Ghost's Castle".