Since it was a rare comic book that made it into our home I know very little about them (I do remember Wonder Woman). This thread has been fun to read though and you might find Wikipedia's entry interesting.

"The Beagle Boys are a group of fictional characters from the Scrooge McDuck universe. They are a gang of criminals who constantly try to rob Scrooge McDuck and were created by Carl Barks. Their introduction and first appearance was in Terror of the Beagle Boys, in Walt Disney's Comics and Stories #134, although in this story they only appear in the last frame and have no lines. They appear again in the next issue in a similar fashion, in The Big Bin on Killmotor Hill. They first get a more prominent role in the later story Only a Poor Old Man."

Lots more.

The Beagle Boys