A small number of hero-crossovers appear in the Italian "muscleman adventure" subgenre of the late 1950s and early 1960s. Until recently I'd considered choosing, as the best representative of these, 1963's HERCULES, SAMSON, AND ULYSSES. Like most of these mini-epics, the storyline of H,S & U is so conventional as to stifle one's imagination, though there is at least a decent fight-scene between the two strongmen of the title.
Happily, thanks to a contributor to Youtube, I came across a far superior nominee: a broad comedy entitled SAMSON AND THE MIGHTY CHALLENGE. I go into more detail in my review, but suffice to say that Hercules falls in love with a young woman who doesn't want him-- a development that probably never occurred in any other Italian Hercules film. The lady's parents try to stave Hercules with a challenge-- and from a plot-standpoint, the film really is a challenge given to Hercules, not to Samson. They tell Hercules that the gods will not give permission for the marriage unless Hercules can defeat the Jewish strongman Samson.
In addition to once again bringing together Samson and Hercules-- this time in a humorous context-- two other heroes also jump into the mix. One is "Maciste," who began his career in the 1914 Italian historical epic CABIRIA, and who then starred as the hero of various silent films, as well as a horde of muscleman-adventures of the fifties and sixties, many of which were re-titled as Hercules films for the American market. The other is "Ursus," whose name was taken from the novel/film QUO VADIS for a handful of "Ursus" films. The Ursus of MIGHTY CHALLENGE is more like a comic brute rather than a hero in his own right, so he's not really a continuation of the noble fellow who had his own series. Then again, I must admit that almost none of these muscleman films maintain any consistency from one episode to the next. So the Hercules, Samson and Maciste of MIGHTY CHALLENGE are similarly not in line with any of the previous adventures of those cinema-characters, much less any mythic or literary forbears.
The highest compliment I can pay the film is to say that while most Italian knockabout comedies aren't nearly as funny as their makers think they are, this one actually brings the goods.