No one quite knows for sure what the Esophagor is but his monstrous appetite is as clear as day. Many a Neopet has gone missing when they strayed too close to the Esophagor. However, if you take on one of his quests for food he may reward you with something.
He also has a brief appearance in Neoquest II, refusing to let Rohane and his friends through to Edna's Tower. He's the final boss of the fourth chapter, the Haunted Woods.
Showww Yyyouuur Ffaacee, Yyoouu Coowarrrdd!
Iit’sss youuuu! Yyyyouu aarre theee oonnne whhoo wennntt too geettt myy diinnerrrr laassst nnniigght annnd neeverrrr caammme baaack. I aammm sssstiiill aannggry aannd I aamm sstiiill huuungryyy. Heeeyyyy! Thaaat’sss MMIIINEEE! Cooomee BAAAAACCKKK! I WIIILLL GGEEETTT YOOUUUUU!!
Completing the Esophagor's quests is the only way to complete a Brain Tree quest.