BRIAN DONNELLY, THE 37-YEAR-OLD PAINTER, designer and master collaborator who goes by the handle KAWS—a name he began tagging on walls, billboards and trains as a teenager in his hometown of Jersey City, New Jersey, because, he says, he liked how those letters looked together—has, for perhaps too long now, been tagged as a street artist. Donnelly certainly got his start that way. Long before he could sell a group of paintings for $315,000, as he did earlier this year at the Paris-based Galerie Perrotin's inaugural Asian show in Hong Kong, or float an enormous balloon of his own design in this month's Macy's Thanksgiving...