John D. Rockerduck
Like the others on this list, Rockerduck is an American creation who's much more notable outside the United States. Created in 1961 by Carl Barks, he was only used in one Barks comic. But he found his fame through the Disney Studios program, appearing in several stories around the world, especially in Italy.
Don Rosa, Barks' true successor and biggest fan, brought back Rockerduck in his Eisner Award-winning epic The Life and Times of Scrooge McDuck. In that story, Rockerduck grew up poor and clawed his way to the top like Scrooge, albeit with a fortune inherited from his father.
The first season season of DuckTales established the show's version of the Duckburg Billionaires' Club, to which both Scrooge and Flintheart Glomgold belong.
Bubba the Caveduck
Bubba is probably the most familiar on this list, as he was created for the original DuckTales. As played by the famed Frank Welker, Bubba first appeared in the "Time Is Money" arc that opened that show's second season, along with his pet triceratops, Tootsie, and was a fixture of the show thereafter. Given his prehistoric origins, we can easily assume that a similar time-travel adventure will be how he meets up with the new version of the Duck family.
The oldest character on this list by far, Della was first mentioned in 1937 in the Donald Duck newspaper strip, and in the 1938 cartoon "Donald's Nephews," where she was named Dumbella. She initially sent her triplets to live with Donald on a temporary basis until their father returned from the hospital (where the kids had sent him after putting firecrackers under his chair), she never appeared again.
In comics, Della has only appeared either as a child or in flashbacks, with her appearance in "The Shadow War!" marking her onscreen debut. Clearly, her reuniting with her family will be a big part of the new season, but could we maybe also learn who the triplets' father is after more than 80 years?
Starring David Tennant, Danny Pudi, Ben Schwartz, Bobby Moynihan, Kate Micucci, Beck Bennett, Toks Olagundoye and Tony Anselmo, new episodes of DuckTales debut Saturdays at 7:30 a.m. ET/PT on Disney Channel.