Knatte, Fnatte och Tjatte

From Wikipedia

Huey, Dewey and Louie Duck are fictional characters of the Scrooge McDuck universe, Donald Duck's three almost identical nephews. They were created by Ted Osborne and Al Taliaferro and first appeared in a newspaper comic strip on October 17, 1937.

According to interviews by Taliaferro they were originally named after two political figures and an animator of the time:

Huey was named after Huey Pierce Long of Louisiana.
Dewey was named after Thomas Edmund Dewey of New York.
Louie was named after animator Louie Schmitt.