Name: Jo-Jo (Jesse McCartney)
Hometown: Who-ville
Occupation: Kid, the Mayor's only son
Talent: Maintaining a low profile, music
Favorite Pastime: Inventing new ways to make music
Description: Jo-Jo loves to make noise but doesn't speak much at all.
Name: Vlad (Will Arnett)
Hometown: A scary cave above the Jungle of Nool
Occupation: Evil villain
Talent: Theatrical flair
Favorite Pastime: Aeronautics and practicing his villainous laugh
Description: Vlad is a Russian black-bottomed eagle who loves to do the dirty work around the jungle.
Name: Morton (Seth Rogen)
Hometown: Jungle of Nool
Occupation: Horton's friend
Talent: Staying out of trouble and hoping Horton joins him
Favorite Pastime: Eating twice his weight in cookies
Description: Morton is a little blue mouse. What he lacks in size, he makes up for in energy!