Donald Duck universe
Donald Duck and his maternal uncle Scrooge McDuck received nearly equal exposure in comics. Other primary characters include Donald's three young nephews Huey, Dewey, and Louie, and girlfriend Daisy Duck.
Duck family (Disney)
In the story "The Good Old Daze" by Tony Strobl, Grandpa Duck (an older Humperdink) appears in flashback taking care of little Donald along with Grandma. He's portrayed as a dedicated but rigorous grandfather. Grandpa's real name wasn't revealed in this story, but in an untitled one from 1951, where an old lover of Grandma called Humperdink has a cameo appearance. Don Rosa considered that this character became Donald's grandfather. In this same story, Grandma remembers an occasion where she and Humperdink heard one of her favorite songs. She says to herself, "I remember the band played that for Humperdink and me at the Fish Peddler's Picnic in 1905!". Besides, Grandma finds the ruined coat Humperdink had used to let her not step on a mud puddle and some romantic letters addressed to her written by Humperdink. Then she remembers some sweet names Humperdink used to refer to her in those letters.