This year marks the 250th anniversary of the Creed brand and, to pay tribute to many of its distinguished clientele, a selection of letters is on display through December at the Creed boutique at Madison Avenue at 67th Street, in Manhattan. Included are letters from President and Mrs. Obama, Crown Prince Felipe and Crown Princess Letizia of Spain, members of the British royal family, Olympic gold medalists and others.  Creed is the world’s only privately held luxury fragrance dynasty passed from father to son in an unbroken line since 1760. This fall, Olivier Creed, sixth-generation master perfumer of France, presents Aventus, a new fragrance for men, inspired by Napoleon. In the classic Creed flask design, which dates to the Napoleonic era, Aventus features black leather wraps and a silver emblem of a horse and rider.