Uncle Trillby was a wealthy uncle of Jack the Clown who appeared in the Adventures of Jack in the Box series of comic books during the Jack in the Box Bunch era.
He is depicted as a mature white male with a top hat and bolo tie. He owned a mansion (which Onion Ring Thing thought was haunted), a ranch featuring an oil well, and a horse named Hermione.
Uncle Trillby was depicted as knowledgeable and ever-ready to share his knowledge with the Jack in the Box Bunch, occasionally through song.
He repeatedly refers to Jack and his friends as "young persons" even though the white-haired Hamburgermeister is presumably older than him.