Understanding Media (1964):
What the Orient saw in a Hollywood movie was a world in which all the ordinary people had cars and electric stoves and refrigerators. So the Oriental now regards himself as an ordinary person who has been deprived of the ordinary man’s birthright. That is another way of getting a view of the film medium as monster ad for consumer goods. In America this major aspect of film is merely subliminal. Far from regarding our pictures as incentives to mayhem and revolution, we take them as solace and compensation, or as a form of deferred payment by daydreaming. But the Oriental is right, and we are wrong about this. In fact, the movie is a mighty limb of the industrial giant. (294-295)

Address at Vision 65 (1965):
The 16th Century created the public as a new environment. This completely altered politics and altered all social arrangements in education, in work, and in every other area. Electric circuitry did not [continue to] create the public; it created the mass, meaning an environment of information that involved everybody in everybody. Now, to a man brought up in the environment of the public, the mass audience is a horror, it is a mess. In the same way, the public was many-headed monster to a feudal aristocrat.

The Hardware/Software Mergers (1969):
When figure and ground merge you have the monster.  

Further Thoughts on Icons (1970):
The TV camera is a Cyclops, a one-eyed monster, which merges the gestalt of figure and ground and turns the viewer into a kind of hunter.

Advice for Universities of the Future (1971):
In the big universities of today the community of the university itself has become as big as a city, as a big city. Universities of 20 to 30 thousand students no longer represent universities at all but represent cities. The modern university, big metropolitan universities, have merged figure and ground — university and community — in what is in effect a monstrous situation. When you merge the figure and ground you have a monster. King Kong is the image of modern man’s service environments stretching out to such size that they crush him. King Kong is our own man-made environment stepping on us.

McLuhan letter to Jim Davey Sept 29, 1971:
The really devastating programming [in the formation of modern society] is the destruction of perception and sensitivity by the creation of vast environments far exceeding human scale. The King Kong fantasies are direct expressions of the feeling most people have in their environments which have become monsters. Yet, the best intentioned bureaucrats in all governments are busily engaged in creating bigger and blacker King Kongs every day of the week. (Letters 441)

Take Today, ‘From Piles of Refuse to Monolithic Slums’  (1972):
When “order” is pushed to extremes (…) [it] becomes ordure. (…) The engulfing of the human scale in providing living accommodation by high-rise creates the hardware monolith where figure and ground grind each other to numerical bits. (…) This is the antisocial monster. The slum is the reverse, but more tolerable. Multiple families crowded in single dwellings turn the environmental ground into figure. This is the social monster. The social monster of the swarming slum has many values of diversity and great powers of endurance [aka ordurance]. Its antisocial opposite, the high-rise “slum”, has no [such] power of survival [via ordurance] (28-29)

Take Today, ‘Gigantism: the nemesis of classical elegance’  (1972):
Gigantism is compelled to grow until collapse. Adaptability is absent. Survival demands an “unthinkable” reversal of scale and pattern. At least, this megalithic monster of moreness tells us we are in the domain of Lord Kelvin, where everything can be said in numbers. It happens that Kelvin spent his life striving to reach absolute zero: the giant omission. Little did Kelvin realize how the numbers racket would be developed in economics and in the studies of the psychologists. His dream of absolute zero has been realized many times in the social sciences but remains a mirage for the physicist. (108)

Take Today, ‘Market-Anti-Market Merger’ (1972):
In Catch-22, the figure of the black market and the ground of war merge into a monster presided over by the syndicate. When war and market merge, all money transactions begin to drip blood. What has happened to war and market in today’s new “software” age is that both involve total commitment in contrast to the specialist “hardware” world of the nineteenth century. The contrast can be observed in the figure-ground relations of the slave market compared with the labor market. Labor is one thing; man as a commodity is another. Today, modes of business and warfare alike tend to blur these distinctions. (211)

Take Today, ‘The Capsized Organization Chart’ (1972):
nature itself performs a figure/ground merger, an OUROBOROS monster, uniting earth and air. (The worm OUROBOROS, which ate its own tail, is the ancient mythic symbol of a world that survives by endlessly devouring itself.)  (254)

The Argument: Causality in the Electric World (1973):
This music [of Marx and Engels] is worse than it sounds”, for it is played literally by eye without ear. Although its epistemology is dialectical, its ontology still rests on abstract Greek Nature. Marx and Engels saw conflicts of old figures as creating [revolutionary] grounds (…) while they remained oblivious of the new information surround that had [already] transformed their assumptions. They were attempting to match [!] the concepts of an earlier age to the experience newly visible in the “rear-view-mirror” of the 19th century. They were
unaware that percepts of existence always lie behind concepts of Nature. Their hidden hang-up was the visual bias of all “objectivity” [and “subjectivity”], whether “materialist” or “idealist.” (…) While the “subjectivist” puts on the world as his own clothes, the “objectivist” supposes that he can stand naked “out of this world.”  The ideal [goal] of the rationalist philosophers still persists [on both sides]: to achieve an inclusive “science of the sciences.” But such a “science” would be a monster of preconceived figures minus un-perceived grounds.

Interview With Marshall McLuhan: His Outrageous Views About Women (1974):
Horror shows are just a record of what people think has already happened to themselves. Exorcism is a picture of what they feel they have been through.

On the Evils of TV (1977):
[TV is] literally a tribal monster like the Minotaur from Greek mythology trapped in a maze of sensation. This Bull-man monster swallowed humans lost in the maze. And that’s exactly what TV does (…) our young are fed to the Minotaur1

  1. For further McLuhan takes on the minotaur, see Minotaur.