Gladstone is a lazy and infuriatingly lucky creature who never fails to upset his first cousin Donald Duck. Gladstone's luck defies Probability and provides him with anything he desires, with hardly the need of effort. His philosophy in life is summarised in leaving everything to chance and taking advantage of opportunities as they come. As Don Rosa has commented on the character " Gladstone is unwilling to make the slightest effort to gain something that his luck cannot give him, and, when things go wrong, he resigns immediately, certain that around the next corner a wallet, dropped by a passer-by, will be waiting for him". For all his luck Gladstone has no achievements to pride of and no true ambitions, as he is incapable of long-term planning. All this in stark contrast to his relative Scrooge McDuck who is also capable of taking advantage of opportunities but works hard to create favorable for him situations, is strongly motivated by his ambitions and takes pride in forming his fortune by his own efforts.
Gladstone finds working for a living deplorable and has held only one job in his lifetime; so ashamed was he at being forced to work that he hid his salary (one coin) in a safe. He is a rival of Donald for the love of their common distant cousin Daisy Duck. He is considered among the prime candidates for Scrooge McDuck's succession. For all these reasons he and Donald have formed an intense rivalry to each other. Gladstone's arrogance and outrageous luck, combined with Donald's own ego and belief he can still best him despite all odds - or as Don Rosa's version of Scrooge comments "Donald's eternal tendency towards self-destruction" - have set the stage for many stories featuring their confrontations.
His exact relation to the Duck Family Tree is somewhat uncertain. In Carl Barks' original version of the family tree from the 1950s, Gladstone was the son of Luke the Goose and Daphne Duck who died by overeating at a free-lunch picnic. He was later adopted by Matilda McDuck and Goosetave Gander. Later, Barks is reported to have done away with the adoption, but no stories denying the event were published. In a more recent version by Don Rosa, Daphne Duck married Goosetave Gander and the two were Gladstone's parents. In his stories that is the case. In his story "The Sign of the Triple Distelfink", first published on February 4, 1997, he added the fact that Gladstone was born on the day of Daphne's birthday on 1920, under the protection sign of the Triple Distelfink, and that he has inherited his mother's luck.
A number of recent Italian stories feature Gladstone's protector Goddess appearing in person. That is Fortuna ,Goddess of Luck, the equivalent in Roman mythology of Tyche, Goddess of Luck in Greek mythology. Notably in "Gastone e il debole dalla Fortuna" ("Gladstone and the struck of Luck"), by Enricco Faccini and Augusto Macchetto, first published on March 24, 1998. In this story the Goddess takes mortal guise to be able to date her favorite duck and appears to be love-struck with him.
Gladstone appeared briefly in the animated series DuckTales. His voice actor was Rob Paulsen (March 11, 1946 -), later noted for playing Pinky of Pinky and the Brain. Otherwise Gladstone is unknown to animation fans. But he is a prominent character of the Scrooge McDuck Universe and familiar to its readers.