The media in general have made much of the success of the films set in the Marvel Cinematic Universe. Certainly such success is unusual. That having been said, the existence of a shared universe, even one in film and television, is not terribly unusual. Indeed, there were shared universes in film and television well before the Star Wars Expanded Universe and the Star Trek Universe. Indeed, it appears that at least one shared universe might pre-date the medium of comic books where it is sometimes assumed the concept of shared universes originated.
Indeed, one of the earliest shared universes is often referred to as the "Cthulhu Mythos" or the "Lovecraft Mythos". Arguably starting with his story "Dagon" (published in 1919), H. P. Lovecraft developed his own world with its own mythos in which his stories were largely set. Eventually many of the writers with whom Mr. Lovecraft corresponded (including Robert Bloch, Robert E. Howard, Clark Ashton Smith, and so on) would introduce elements of the Cthulhu Mythos into their own stories. During H. P. Lovecraft's lifetime the Cthulhu Mythos was never systematised or formalised, but following his death writer August Derleth would set about a systematisation of what he termed "the Cthulhu Mythos". Since then writers from J. Ramsey Campbell to Stephen King have written stories set in the shared universe that originated with H. P. Lovecraft.
Of course, in the early to mid-20th Century the concept of a shared universe would have its biggest impact on the medium of comic books. In fact, the origins of the Marvel Universe go all the way back to Marvel Mystery Comics #9 (July 1940), in which the Human Torch met and battled The Sub-Mariner. It was the first major crossover in the history of comic books. Of course, while Marvel Mystery Comics #9 established that the Human Torch and The Sub-Mariner existed in the same world, it said nothing of the other characters published by what would become Marvel Comics.
While shared universes would play a major role in comic books, that is not to say that they would not play a role in film prior to the Seventies. In fact, one of the earliest shared universes may have been that of Hal Roach Studios. Hal Roach Studios is perhaps most famous for its various comedy shorts, including the Laurel & Hardy shorts, the "Our Gang" shorts, the Thelma Todd and Zasu Pitts shorts (later Thelma Todd was teamed with Patsy Kelly), and so on. It was from a very early period that characters from one series of shorts might make a cameo or even a longer appearance in another series of shorts. Indeed, it was in the 1927 Charley Chase short ""Now I'll Tell One" that Laurel & Hardy appeared. Laurel & Hardy would also appear in the 1931 Thelma Todd and Zasu Pitts short "On the Loose". Of course, here it must be pointed out that the Hal Roach shorts did not have any sort of real continuity and such crossovers were rare, so some may argue against there even being a shared "Hal Roach Universe".
While some may might argue against the characters of the Hal Roach comedy shorts existing in the same universe, there can be no doubt that the Universal Monsters share the same reality. Universal made its first horror film in 1913 (when the company was still called Independent Moving Pictures Company), an adaptation of Dr. Jekyll & Mr. Hyde. Later in the Silent Era Universal would have success with adaptations of The Hunchback of Notre Dame (1923) and The Phantom of the Opera (1925). The studio would follow the success of those films with such movies as The Cat and the Canary (1927) and The Man Who Laughs (1928).
While Universal had a great deal of success with horror during the Silent Era, however, it was two films made at the advent of Sound Era that would cement the studio's association with the horror genre. Dracula (1931) and Frankenstein (1931) proved to be such phenomenal successes that they not only led Universal to make more horror films, but nearly every studio in Hollywood over the next several years. This cycle towards horror movies (which I refer to as "the first Golden Age of Horror Movies") wound down in 1936. It was in 1939 that Universal resumed making horror movies with the second sequel to Frankenstein (1931), Son of Frankenstein. Son of Frankenstein started a whole new cycle of horror movies, including The Mummy's Hand (1940), The Wolf Man (1941), and The Ghost of Frankenstein (1942).
While it is well known that the Universal Monsters shared the same universe, what is less well known is that there was a rather extensive shared universe in the early days of episodic television shows in the United States. Having scored a major success with one TV series produced by a major Hollywood studio (Disneyland, produced by Walt Disney), the American Broadcasting Company (ABC) approached Warner Bros. about producing television shows for the network. The first show Warner Bros. produced for ABC was an umbrella series called Warner Bros. Presents. Warner Bros. Presents consisted of three rotating shows: Casablanca, King's Row, and television's first hour long Western Cheyenne. Of the three Cheyenne would be the only one to prove to be a success, perhaps because it was among the first shows (along with Gunsmoke and The Life and Legend of Wyatt Earp) in a long and very prolific cycle towards Westerns in the late Fifties. As a result of its success, Cheyenne would be the first of many Westerns produced by Warner Bros. and the first set in a rather extensive shared universe.
If there had been any doubt that the heroes of the Warner Bros. Westerns all existed in the same universe, that doubt would have been erased by the 1960 Maverick episode "Hadley's Hunters". In the episode Bart Maverick (played by Jack Kelly) finds himself framed by a crooked sheriff and as a result seeks help from every Warner Bros. Western hero who still had a show on the air. Bart visits Cheyenne Bodie (played by Clint Walker) of Cheyenne, Marshall Dan Troop (played by John Russell) and Deputy Johnny McKay of Lawman, Tom Brewster of Sugarfoot, and Bronco Lane of Bronco. "Hadley's Hunters" not only made it clear Warner Bros' various Western heroes existed in the same reality, but that their detective shows might well take place in the 20th Century of that reality as well. Among the people that Bart visits in an effort to clear his name is a stableboy played by Edd Byrnes, who played Kookie on Warner Bros' detective show 77 Sunset Strip. The address at which the stableboy works is "77 Cherokee Strip". While Edd Byrnes' appearance is most certainly an in-joke, it seems possible that the stableboy was an ancestor of Kookie on 77 Sunset Strip. In other words, 77 Sunset Strip is part of the shared universe of Warner Bros.' Westerns!
Warner Bros' shared universe in which their Westerns and detective shows took place did not have a particularly tight continuity, nor were crossovers as common as the above summary might make it seem (we are taking about a period of many years here). Regardless, outside of comic books and the Cthulhu Mythos, the Warner Bros. shared universe of Westerns and detective shows was one of the most extensive shared universes up to that time. In fact, in television it would not be matched until the Star Trek shared universe began developing with the debut of the sequel series Star Trek: The Next Generation in 1987. Even today, in an era of such franchises as CSI and Law & Order, it remains an impressive achievement.
While the Marvel Cinematic Universe is certainly an impressive achievement, then, in many respects it is hardly an isolated event. Not only did shared universes exist in media other than comic books well before the development of the Marvel Cinematic Universe, but some of them were quite extensive. In fact, it seems that not only could Universal dust off its shared universe of Universal Monsters, but so could Warner Bros dust off its shared universe of gamblers, lawmen, gunfighters, and detectives. Although shared universes might seems like a new concept to me, they have actually been around for awhile.
