The “imaginary friend” tends to be conjured up by a child. A manifestation of inner vision, it is a being invisible to everyone except its creator. But imaginary friends are not just for children. “Even now, whenever necessary,” the choreographer Paul Taylor has said, “I still summon forth the old geezer—in theater programs, for example, to credit him for costumes that I’ve designed, ones for which I prefer not getting the hook.” Like Taylor, some artists have never let go of their “geezers.” In this exhibition, paintings, sculptures, and video installations explore the creatures that inhabit this fantasy realm. Artists on view include Paola Pivi, Kasper Bosmans, Polly Apfelbaum, Meschac Gaba, Afra Eisma, Pipilotti Rist, and Martin Creed. For many of them, it is their first show in Spain. —Elena Clavarino