Play often rewards us with a thrill or a sense of wonder. But, just over the edge of play, uncanny objects like dolls, automata, robots, and realistic animations may become monstrous rather than marvelous. Drawing from diverse sources, literary evidence, psychological and psychoanalytic theory, new insights in neuroscience, marketing literature, robotics, and new testimony from survey respondents, this article pinpoints a moment when surprise turns to shock and play drains away. Play is surely difficult to define, but demarcating its porous boundary--where what one moment creates joy can, in the next, cause dread--is a useful step toward describing this shifting phenomenon.