Arpin Lusène , also known as the Black Knight, is a male dognose.
Arpin Lusène, heir of Arsène Lupin, is an extremely talented gentleman-thief, whose talents have long made him a millionaire. Lusène, who prides himself on never having been photographed, operates under the alias of the Black Knight. Much like the original Lupin, Lusène is known for leaving calling cards on the scenes of his many crimes, for his impeccable sense of honor and "fair-play", and his womanizing.
Towards the middle of the 20th century, Lusène, who enjoyed every luxury wealth could offer and was growing bored with his criminal career, decided to retire. However, his personal pride would not allow him to do so unless he could retire with one last feat of thievery to top them all, and he became fixated on the idea that only stealing all of Scrooge McDuck's fortune would be a fitting final bow for him. Ever since, Lusène has acted as an "affectionate nemesis" for Scrooge.
Shortly after reaching this decision, Lusène got the opportunity to make his moniker of "the Black Knight", and his reputation for invicibility, much more literal, using an Omnisolve-coated armor on two separate occasions in his attempts to rob McDuck. The suit of armor was eventually launched into orbit by Scrooge, and though Lusène has made some preliminary research to get it back, he does not appear to have yet done so.
Behind the scenes
Arpin Lusène was created by Don Rosa in 1998 in the story The Black Knight. Lusène is an obvious homage to Arsène Lupin (a fictional gentleman-thief from French literature). He also takes his over-the-top accent from Inspector Clouseau, the clueless detective protagonist of Blake Edwards' The Pink Panther movie series, portrayed by Peter Sellers.
Arsène Lupin himself, incidentally, also has a direct counterpart in the Disney comics universe. Considering that Lupin was known, in the original novels, to be something of a Casanova, it is quite possible (and the timelines fit) that Lusène is actually an illegitimate son of Lupin's.
In French translations
In French translations of Rosa's stories, Arpin Lusène's name, which, while "French-like", is actually quite odd to actual French ears, was changed to Lucien Arpène, a different play on the syllables of Arsène Lupin which gave him an actual, moderately-common French given name, "Lucien". As for his over-the-top French accent, and the associated running gag of characters misunderstanding his words because of it, it was replaced with Lusène using very refined and old-fashioned vocabulary, which the more down-to-earth Duckburgers never understood. (Due to a translation slip-up, however, Scrooge still refers to Lusène's "French accent" in one particular speech bubble in The Black Knight.)