Huey, Dewey and Louie‘s father is first mentioned in Donald sunday strip in 1937 by Al Taliaferro and Ted Osborne, in a letter sent by Della Duck to Donald, he never had his face revealed.
Don Rosa included him in his family tree, but hid his face, Della Duck appeared in comics written by Rosa, in Dutch comics and even in the DuckTales 2017 series, but the father of the triplets is not even mentioned.