Grandpa Beagle, also known as Blackheart Beagle, is the grandfather, founder, and sometimes leader of the Beagle Boys. He first appeared in the Carl Barks stories The Fantastic River Race (as Blackheart Beagle) and The Money Well (as Grandpa Beagle).
In Scrooge's flashback in The Fantastic River Race, Blackheart Beagle looks very similar to his children and his present-day grandkids, albeit with a long mustache, a black and blue uniform, and sailor hat. In The Money Well, Grandpa Beagle appears as an elderly Beagle Boy with the number 186-802.
Grandpa Beagle was used again in 1962 by Rodolfo Cimino, as the Beagle Boys' leader, in the comic Zio Paperone caporale d'assalto. In Italian stories, Grandpa Beagle has the word "Grazia" instead of a prison number, indicating that he may have been pardoned, though he is often seen in (or escaping from) prison. Sometimes he is portrayed in the same physical shape as his grandkids, sometimes thinner, and sometimes he's thin when all the Beagle Boys are shown as such.
- Just like John D. Rockerduck, Grandpa Beagle was used only once by his creator, Carl Barks, but became popular in Italian comics.
- Barks did not intend for Blackheart Beagle from The Fantastic River Race and Grandpa Beagle from The Money Well to be one and the same character when creating the characters. For unknown reasons, Don Rosa depicted them as the same character in The Life and Times of Scrooge McDuck.
- In some European productions, such as his character profile poster in the German Micky Maus Magazin, Grandpa Beagle was said to be the Beagle Boys' father rather than their grandfather.
- Brazilian writers depict him as a respected semi-retired crook who sometimes gives advice to the Beagle Boys.