Has Gladiator ever tangled with Thor (or King Thor)? I'm interested to see how that fight would go.
Yes. Coincidentally, it was in this issue, which Majin Boo seems to have posted just for the hell of it:
this is one of my favorite covers
This was Jurgens' early Thor, who transformed into basically a clone of Jake Olson (who shall henceforth be known as "Fake Olson") whenever he was away from Mjolnir for more than 60 seconds.
Zarrko pulled a future version of Gladiator into the present in an attempt to assassinate Thor before he could become King Thor (Jurgens was big on the foreshadowing at this point). Gladiator basically lays into Thor with no explanation and Thor struggles to defend himself and protect his alter-ego's girlfriend's daughter while repeatedly questioning why Gladiator's so intent on killing him. Gladiator ignores him and pretty much dominates the first part of the fight, and he ends up knocking Thor away from Mjolnir and into an ambulance. 60 seconds pass and Gladiator opens the ambulance to find Fake Olson unconscious. That could be counted as a win for Glads, but it's debatable.
Tarene shows up and tries to fight Gladiator but gets incapacitated when he throws a water tower on her and freezes its contents around her; but she buys Fake Olson enough time to wake up and transform back into Thor. Thor, tired of asking for answers and getting nothing but a thrashing in response, goes on the offensive. They make their way over to an airport runway, and their fight is interrupted by a landing plane. They call a truce to help the plane land (it went out of control after the pilot saw two dudes suddenly appear in his landing zone), and then Thor blasts Gladiator in a bit of a cheap shot. Gladiator recovers quickly, but Thor says he's gonna stop holding back and basically beats the unholy hell out of Glads. Then Tarene shows up again, pissed at how Glads humiliated her, and lets loose a blast that leaves Gladiator a weakened, blathering mess. They take him back to Odin and Odin, who also knows of Thor's future as King Thor, sends Gladiator back to his own time, claiming that it's not the place or the time to divulge that information to anyone yet.
A couple of factors to consider about the dynamics of this fight:
1) Thor is weakened by his stupid 60-second rule, which we all thought we were free from after Simonson did away with his Don Blake side, but Jurgens proved we were unfortunately mistaken about.
2) Gladiator was likely weakened by the fact that it was a future version from, apparently,
way in the future. Thor comments that Glads looks markedly older than he remembered him, and I assume Thor doesn't admire Glads' features regularly, so the fact that he noticed the aging to be so profound says a lot.
3) Thor makes it pretty clear that he's holding back against Glads for most of the fight--the facts that he's protecting Jake Olson's girlfriend's brat, that he considers Glads an ally and is thus hesitant to fight him, and that he sticks to the defensive while questioning Glads' motives for a big part of the fight support this.
4) Tarene kept butting into this fight, so it's hard to say that Thor
or Glads won definitively at any point. Glads seemed to win round 1, then Tarene screwed it all up, then Thor seemed to win round 2 before Tarene again screwed it all up.
So basically Glads and the real Thor have fought, but it was inconclusive in just about every respect.