The Creepy Steeple Boo

The Creepy Steeple Boo is a Boo from Creepy Steeple in Paper Mario: The Thousand-Year Door. He is the Boo that asks Mario "How many Boos just came out?" after Mario frees the two hundred Boos from Creepy Steeple. He will drop an Ultra Shroom and call Mario a "math nerd" if Mario guesses correctly, while if Mario gets it wrong (50 or 100) he will call Mario a "foolish mortal" and drop a coin. It is unknown if he was actually one of the Boos that joined in to make Atomic Boo, as he is presumably a friendly character throughout the game. It is unknown if he was also referring to himself when he asks how many Boos came out.

Later, he sends Mario an e-mail saying that he is thankful for Mario freeing him and his friends; he also reveals in the e-mail that there are many secrets for Mario to find in his home of Creepy Steeple. That e-mail shows his dislike for technology and seemingly frequent criticisms of himself.

E-Mail
Are you Mario? Did this e-mail...did you get this e-mail? Look, technology freaks me out, so if you're not Mario, please destroy this e-mail, OK? But if you are, thanks for saving my captured friends. I figured I'd share a hot tip with you as thanks, so here it is: there's still lots of treasures in Creepy Steeple! Of course, knowing you, you've probably already found it all...ugh...I'm so useless... Well, enjoy your not-so-useless adventure. The Creepy Steeple Boo
 * Mail?