The Letter "p"
The Letter "p" is a special item in the game Paper Mario: The Thousand-Year Door.
Mario and Vivian needed The Letter "p" to guess Doopliss's name, because while guessing his name, their letter options lacked this letter. This was also a very clever way to prevent people from cheating (by looking up Doopliss's name on sources such as player's guides and the internet). Although a capital P is always available, it won't work, for the spelling must be case sensitive.
To find the letter, Mario is forced to use Vivian to access a secret portion under the well in Creepy Steeple, using her Veil power. There, Mario can roll up into a tube and access a treasure room, where one of the chests contains the letter. By using Veil again, a parrot in the room reveals Doopliss's name for the player.
Trivia
- Doopliss is called "Ranperu" in Japan. The missing letter in the Japanese version is "n" (though in the katakana alphabet) rather than the American "p".
