Gladstone Gander is Donald's cousin. He is always extremely lucky, but he's also extremely lazy, always counting on his luck to fix everything for him.
His extreme luck comes from an subconscious ability to alter probability in his favor. This has the side effect of giving bad luck to others around him, most often Donald Duck.
For some reason, bad luck sometimes falls upon him too. It`s not known why (other than that the writers don`t like him to win all the time). It`s probably karma.