Gruffy, Ruffy and Tuffy Van Dukke, also collectively nicknamed the Murdernephews, were a trio of young anthropomorphic ducks.
Even more bloodthirsty than their tutor, these kid-pirate ancestors of the Duck family sailed with the infamous Captain Ringtail Van Dukke until Ringtail decided to go straight. They still crewed his ship (albeit reluctantly) on his first (and, as it would turn out, final) commercial errand, ferrying Pinchpenny Van Dukke's gold, but were left behind with a fond parting letter by Ringtail when he began his centuries-long quest to finding the gold again after it was lost in the ensuing shipwreck. Their later fate is unknown.
Behind the scenes
The Van Dukke nephews appear the 1992 story The Last Voyage of Ringtail Van Dukke.
It is not altogether clear what side of the Duck family the Van Dukkes he related to; in the original version of the story, their uncle's last name is Duck, as opposed to Van Dukke, suggesting they are an ancestor of the Duck family rather than the McDuck clan. However, Ringtail's uncle Pinchpenny is explicitly identified as an ancestor of Scrooge McDuck's.