Bonetail

In Paper Mario: The Thousand Year Door, Bonetail is a large zombified Dragon, living at the bottom of the Pit of 100 Trials.

He is the oldest member of the "tail" family, older than both Gloomtail and Hooktail. As his name implies, he is merely a skeleton of a Dragon, implying that he has been living far longer than the other members of the family. He was once a minion of Shadow Queen, but has apparently stopped serving her. Any actions outside of the Pit of 100 Trials, if any, are unknown.

After Mario and his teammates defeat him, they'll earn the Return Postage Badge.

Stats (Paper Mario: The Thousand Year Door)
HP: 200, Attack: 8, Defense: 2

Tattle: That's Bonetail. He's the older brother of Hooktail. ...So old he's just bones, in fact. Now THAT'S old. He has various breaths that might confuse us or put us to sleep. When his HP gets low, he'll recover...or reanimate, as the case may be. He's probably stronger than the last boss, seriously! Let's do this right!