Louis Throwing the Coat (Dramatic Irony)
At Louis' party, he collects someone's coat and throws it into his bedroom onto the bed. He doesn't look into the bedroom, but the viewer sees that he has just thrown the coat onto one of Gozer's demonic dogs that is sitting on the bed in the dark. Louis goes back to the party, blithely unaware of the threat that is so nearby. When the guests grow confused hearing the demon's growls, Louis still doesn't sense that something is amiss, assuming instead that someone brought their dog. In these moments, the viewer knows more than Louis, which creates a particularly suspenseful dramatic irony; we know that any minute, the demon could attack the partygoers, but Louis has no idea.
No One Helps Louis (Situational Irony)
Not long after Louis learns what's making the growling noises in his bedroom, he must set to work convincing others that he is in danger. He runs out of his apartment building screaming for help, but the doorman simply shrugs as if to say "only in New York," and laments the fact that someone brought a cougar to a party. The demon is hardly a cougar, but the New Yorkers outside the building are so jaded to outrageous events that they do not intervene or even register as unusual the fact that Louis is being pursued by a demon from a paranormal dimension. This creates an irony because while the viewer (and Louis) expects someone to help him, no one takes his problem seriously enough. This continues when he goes to Tavern on the Green and screams through the glass for help. People barely move, and simply shrug off the incident. Meanwhile, the demon is about to attack and possess him in a matter of seconds.
The Marshmallow Man (Situational Irony)
The figure of the Marshmallow Man is ironic because after Peter urges everyone to clear their minds so that Gozer doesn't take a physical form, Ray cannot help but think of the Marshmallow Man. The Marshmallow Man is a symbol of commercialism and advertising, which contrasts sharply with the primordial and demonic powers of Gozer. Thus the combination of advertising and apocalypse strikes an ironic cord. Equally ironic is the fact that the Marshmallow Man is a figure that Ray loved in childhood; to him it represents wholesomeness and a care-free delight. The Marshmallow Man that Gozer inhabits is anything but wholesome, wearing an evil smirk and using its big fluffy arms and legs to wreak havoc on the Upper West Side. The image of a childhood idol becoming an apocalyptic monster is an unexpected twist.
The Librarian (Dramatic Irony)
The very first scene of the film contains some suspenseful dramatic irony. As the older librarian makes her way through the aisles of books in the basement, the camera follows her around, and we begin to see strange, uncanny occurrences take place around her. They remain out of her view, however. As she walks past the card catalogue, we see drawers open on their own behind her, but she doesn't notice. Then when she is in the stacks, we see books fly across onto opposite shelves, ghostly hijinks that she doesn't clock. Before we know anything about the movie, we can perceive more about the ghostly incursion than the sweet librarian, making for some potent and memorable dramatic irony.
