CROSSOVER MADNESS

 The 1998 MASK OF ZORRO counts as a very minor crossover in that the fictional "Zorro 2.0" is said to be the brother of a "Joaquin Murietta." The real Murietta became a legendary figure with alleged "Robin Hood" traits, and this legend, according to some pundits, influenced Johnston McCulley's story of Zorro. Thus far I've seen no proof of said influence. But even if the movie's version of Joaquin duplicates none of the legend's deeds, clearly the filmmakers used the name to evoke the legend, and this is a very minor charisma-crossover.

NULL-CROSSOVERS #13

 This illustration and a few others like it appeared in DC's Dollar Comic THE UNEXPECTED, which sported inventory stories from HOUSE OF SECRETS and DOORWAY TO NIGHTMARE. Since HOUSE's Abel was a non-diegetic storyteller while DOORWAY's Madame Xanadu was the diegetic star of her stories, all of these "crossovers" are of the null variety. Excellent art by Ditko.

RAR #63: LITTLE SURE SHOT

 During the time Annie Oakley traveled with Buffalo Bill's Wild West Show with her sharpshooter act, her fellow "actor" Sitting Bull dubbed her "Little Sure Shot."

In 1963, the name was applied to an Apache sniper serving with American forces in WWII. This "Little Sure Shot" became one of the regular characters in the Easy Company unit of Sergeant Rock, an elect group that never got killed no longer how many battles they endured.

CROSSOVER MADNESS

Two days after my previous post, I was aimlessly looking through some western comics images, and found my way to a "Classic Comics" post. This post asserted that the first western team up in comics, at least with "Marvel" characters, was when they took their version of Annie Oakley from 1955:

And let her show up, with exactly the same visual design, in WYATT EARP #5 (1956), in the unpoetically titled "The Day Marshal Earp met Annie Oakley." 

CROSSOVER MADNESS

 Historical figures Davy Crockett and Mike Fink, both of whom had taken on semi-legendary status, became associated in popular fiction, resulting in their meeting in two 1955 Walt Disney telefilms, with Crockett played by Fess Parker and Fink by Jeff York.

Eleven years later, in RAWHIDE KID #54, Denny O'Neil and Don Heck authored a one-off story in which Mike Fink met Bat Masterson, even though the real Fink had died thirty years before the birth of Masterson.

CROSSOVER MADNESS

I've read none of the works of L. Frank Baum except the first OZ book, but on researching the author I learned that, thanks to the almost immediate success of that series, he established some loose linkages to other attempted franchises. For instance, a couple of characters from the 1909 ROAD TO OZ show up in the 1912 SKY ISLAND, the second of two books which the author had to drop because they didn't sell well enough to continue. He later had two characters from that short lived series in the 1915 SCARECROW OF OZ, and Wikipedia lists a number of projects which aren't technically Oz books but have loose connections to that universe. So Baum stands as one of the first crossover-makers of the twentieth century.