Bombie the Zombie is a human.
Some time before 1909, a poor African fellow by the name of Bombie was put under a curse by voodoo warlock Foola Zoola and turned into a "zombie": a slow-witted, undying creature who would do Zoola's bidding. In 1909, after Scrooge McDuck burnt Zoola's village for profit, the revengeful Zoola sent Bombie after him, carrying a cursed doll that would shrink Scrooge down to the size of a mouse if he touched it. Bombie could feel Scrooge's presence and thus Scrooge never managed to lose him; however, Bombie had only seen Scrooge without his glasses and sideburns, and, thus, didn't recognize him whenever he got close to him. At any rate, Bombie chased Scrooge throughout the world, including to Greenland and on the Titanic, before Scrooge managed to get another voodoo doctor to freeze Bombie in place for forty years.
In 1949, freed from the spell, Bombie resumed his quest. This led him to Duckburg, where Scrooge McDuck now lived. There, Bombie happened upon Donald Duck, who, unfortunately, looked exactly like the disguised Scrooge Bombie had met in 1909. He gave him the doll, and Donald was struck by the curse. However, to have it lifted, he decided to travel to Africa to pay Foola Zoola. At Huey, Dewey and Louie's insistance, Donald took Bombie with him, for the poor old bloke, his unlife's mission fulfilled, didn't know what to do and cried of homesickness. In Africa, the Ducks last saw Bombie bouncing around because of rubber attached to his feet, progressively knocking down all the members of Foola's tribe by his random bounces.
It appears that Bombie's curse was eventually lifted, and Bombie visisted his Duckburg friends on occasion.