Bootler
Bootler is a Boo butler who works for Lady Bow in Boo's Mansion. He also acts as her personal advisor. Bootler is very protective of Lady Bow, and initially does not want her to join Mario on his quest to defeat Tubba Blubba.
He seems to have a certain connection with Lady Bow's ansestors and constantly reminds her that the ansestors would be displeased if she was harmed in any way.
In his youth, Bootler traveled the globe with Goompa and Koopa Koot.
After Mario defeats the Shadow Queen in Paper Mario: The Thousand-Year Door, Lady Bow and Bootler go to Poshley Heights for a nice (but expensive) vacation.
Bootler has legendary status as a master frightener. He even scares Fice T. and Mario at the entrance of Forever Forest.
"Bootler" is word play off "Boo" and "butler", in case you haven't noticed, and seems to be the only Boo with facial hair in the history of Mario games.