I have written a time or 10 in the past about my great childhood love of two great old TV series, Batman and The Green Hornet, both of which originally aired on ABC in the 1960s. Both shows were produced by a gentleman named William Dozier, who - in an effort to garner a larger viewership for The Green Hornet, which wasn’t quite bringing in the ratings of the other show - came up with the idea of having the Green Hornet and his sidekick Kato appear in an episode of Batman.  

Now you have to understand that, for kids watching TV in that era, seeing Batman and the Green Hornet together sharing a single adventure was a BIG DEAL. We'd never seen anything like that before. (Okay, to be fair, there had been one similar instance half a decade earlier, when the Lone Ranger turned up in a 1959 episode of Lassie. And, of course, there was that time when Superman turned up in an episode of I Love Lucy. But neither was quite the event that the Batman-Green Hornet team-up was. The "Lassie" episode, after all, was little more than a half-hour PSA for U.S. Savings Bonds. Besides, both the Lone Ranger who met Lassie and the "Superman" who encountered Lucy and Ricky Ricardo were clearly supposed to be actors Clayton Moore and George Reeves - even if neither man was ever referred to by name at any point in either episode.)

For us, the only time heroes from separate and seemingly disparate universes ever teamed up (outside of the comic books, of course, where such things had been going on for years) was when the kid from across the street would bring his G.I. Joe over to play with you and your Johnny West or Captain Action. So seeing real heroes (for such did we view the TV show characters at that young age) actually getting together to fight the same bad guy was nothing short of awe inspiring. Because it made us realize that the fictional universe we so enjoyed playing in was every bit as big as we had daydreamed it to be. 

For those of us who were viewed by just about everyone (including ourselves) as geeky little kids, it was a truly epic moment. 

These days, of course, such events - commonly referred to as “crossovers” by all those geeky little kids who grew up to become geeky adults - are not only far more commonplace, but tend to generate much positive attention and feedback from those who used to make fun of the rest of us for being geeks. It’s not quite as big a deal when characters from “franchise” shows that are already linked with one another - the various CSI, NCIS, Star Trek or Law And Order series, for example - turn up on one another’s programs. But when the crossover occurs between two shows that previously had nothing to do with one another... ah, that’s when the giggling starts and the inner geek is set free to revel in the moment.

Fans of the series NCIS: Los Angeles, for instance, almost certainly got a big kick out of seeing characters from that show turn up in episodes of Hawaii Five-O or Scorpion. Old-timers like myself cheered back in the 1990s when the Dick Van Dyke series Diagnosis: Murder had episodes featuring characters (and the actors who originally played them) from such classic TV series as Mission: Impossible, Mannix and Matlock. Characters from The Bob Newhart Show would later turn up on St. Elsewhere and Murphy Brown. An episode of the romantic comedy series Mad About You revolved around the making of a documentary about Alan Brady, the TV comic for whom Rob Petrie worked on The Dick Van Dyke Show

And seeing the character of Detective John Muench - who had already migrated from the series Homicide to Law And Order: Special Victims Unit - turn up in a cameo role in an episode of The X-Files is STILL a topic that can generate much discussion among certain fans of all three shows.

Sometimes the crossover is a little more subtle, focusing not on characters but on background information from other shows - one which sometimes do not even appear on the same network. Earlier this season, a character in an episode of Hawaii Five-O - a more or less traditional crime drama airing on CBS - made a passing reference to a criminal who had been featured in an episode from the previous season of Arrow, a comic book-based series about a costumed crimefighter airing on the CW Network. Some years earlier another CBS series, the quirky small town drama Picket Fences, had an episode which made similar reference to events from an episode of The X-Files, which aired on Fox. Both instances were little more than elaborate in-jokes between series writers who happened to be friends, but in both instances the fans went nuts.

Some of us have even made a game out of such crossovers, using every instance of character crossovers and shared background informational references we can find to weave our own elaborate and intricate fictional tapestries. Some people see it as building on the tradition that began with "The Game" played Sherlockians, and raised to something akin to an artform/science by Philip José Farmer’s creation of the Wold Newton Mythos. Others view it as nothng more than some silly fanboy variation of the game “Six Degrees Of Kevin Bacon.” Call it what you will; it's fun either way.

One of my own personal favorite threads goes something like this: 

Singer-actor Davy Jones played a singer named (surprise!) Davy Jones on a television series entitled The Monkees. Jones later appeared as Davy Jones on an episode of The Brady Bunch, and not long after that also turned up as one of the animated guest stars (again called Davy Jones - or, more accurately, "the famous Davy Jones") on the Saturday morning cartoon series The New Scooby-Doo Movies, which also of course also had episodes featuring appearances by such guest stars as Batman and Robin, the Harlem Globetrotters and Josie And The Pussycats. The kids from The Brady Bunch had their own Saturday morning cartoon (The Brady Kids) that had episodes featuring guest appearances by Superman, Wonder Woman and the Lone Ranger. Superman, Batman and Wonder Woman all appeared together on Super Friends, while Josie and the Pussycats were originally comic book characters who had appeared alongside Archie, Jughead and their friends. (And the cartoon version of the Archie gang interacted with the Groovie Goolies, who once encountered Daffy Duck and some of the other Looney Tunes characters, who in turn have found themselves running into everyone from Mickey Mouse and Roger Rabbit to Errol Flynn's Robin Hood and Michael Jordan...) Meanwhile, the Harlem Globetrotters were the focus of one of the Gilligan's Island reunion movies. 

Throw in the aforementioned Batman-Green Hornet team-up, since the Batman depicted on Super Friends and Scooby-Doo was for all intents and purposes the same version of that character, and you’ve got an interconnected fictional reality of wild and downright mythological proportions.

Silly? You bet! That’s what’s so darn much fun about it. And nobody can take that away from us. So don't even bothering to try.

Besides, it sure beats spending countless hours sitting in front of the TV watching (ugh!) basketball...