Just Hit Him/Headscratchers

Really huge monsters
I've always had a lot of trouble rationalizing how on earth somebody is supposed to fight really, really big monster in close combat. I mean, say I'm playing (not that this is exclusive to games, but in it's the most common there) a game, like Nethack, Warcraft, Heretic, or especially something along the lines of Exile: I'm a guy with a sword, plus maybe a friend or five, we're in our tiles, on our turn; I'm facing a dragon, it takes up six tiles, which is really Units Not to Scale, since it's supposed to be Like, 50+ feet long, but even as is it looks super scary; I step up to it, and hit the movement key to “attack,” which presumably involves doing something with my sword to inflict quite a bit of damage; it then attacks me in such a fashion as to do some damage, while failing to break every single bone in my body from one even glancing blow, or turn me into a spoonful of strawberry jam with a single well-placed stomp; If this lasts more than one round, I also display the ability to block its path, preventing it from trampling over me to turn my back-row Glass Cannon into a teething toy.

Even trying to imagine something more real-world, like a Roman centurion taking on a rhinoceros, I can't imagine any way such a match could be fought if he stood his ground toe-to-toe, no matter what sort of Implausible Fencing Powers he had.
 * Magic? Keep in mind that in most games of that sort, you have variously-enchanted equipment that can do whatever the plot says it can. Also, there's just not as much Spectacle to be had in a monster that curb-stomps everything. (Exception: Godzilla.)
 * The problem with magic is that in most settings, modern and eastern ones at least, dragons tend to be very powerful in terms of magic as well. Or, as in Warcraft III, mature dragons were altogether immune to magic. This has to do with various works (mainly games, but not only) avoiding the Chunky Salsa Rule in the pursuit of balance over Fridge Logic. Though if a 17 meter dragon steps on a human, the remaining salsa won't even be that chunky... Edit: The Orks naturally have the proper solution.

Tearing a head off -- easy or not?
Several of the entries on the main article, especially the Buffy one, suggest that it'd be easier for a monster to just pull someone's head off their body. Now granted, that might be hyperbole, but for the sake of argument let's assume that's a serious suggestion. It doesn't seem to me to be an easy suggestion. You know how Superman shouldn't be able to land a crashing plane by supporting one tiny section of it, because he'd realistically just punch through the metal skin? It seems to me if you had super-strength, you couldn't rip a person's head off. You'd just, I dunno, accidentally crush part of their skull while trying to get a good grip.