Bruno Bischofberger , a legendary dealer who grew so close to the artists he loved that he became something like a collaborator to them, shaping art history along the way, has died at 86. His Zurich-based gallery announced his death on Saturday. Through his eponymous gallery, Bischofberger helped bring a range of American art stars to Europe, becoming a significant force in the market along the way. Founded in 1963, that gallery is still considered one of the most important ones in Switzerland, a country rich with blue-chip art spaces, and remains a mainstay not only in the international art world but also the international art press. Related Articles Among other things, the gallery is known for taking out an advertisement on the back page of every issue of Artforum , a tradition it has continued since the mid-’80s. “Bischofberger’s aesthetic is characteristically Swiss in its incredible consistency,” Artnet News was moved to note in 2015, the year that Galerie Bruno Bischofberger left its St.…