I am curious about one thing: For each of these games, what is the most damage that one can inflict without cheats? (Glitches and other exploits are allowed, but the damage must be from a single damage message.)

For BG1, I think I read something about Strength bonuses being multiplied by backstab, so if you get 25 Strength (by playing through the game multiple times), you could do huge damage by backstabbing as a thief.

For BG2, you could backstab while shapechanged into an Iron Golem, and maybe add Righteous Magic to guarantee maximum damage. You would need to be a Cleric/Thief to actually pull this off, along with the help of at least one mage scroll (used by the item swap glitch). The question is, can you do over 200 damage this way or with a similar method?

Of note, the damage doesn't have to be on an enemy for purposes of this question. This means you might be able to increase the damage by increasing the difficulty.

(If we allow cheats, dealing over 1000 damage in BG2 is trivial; just cheat in the killsw01 and attack with it.)

Just make your own weapon and the (silly) question is moot.

Glitch it is, then. From the originals, the final boss of the expansion, that big demon thing (which requires a quest dagger, too...), can be felled with a single cloudkill spell. Something is wrong and i don't remember the specifics to activate the glitch, but the damage he receives must be very, very large. Googling it might just reveal a youtube video or a more detailed insight into that case...

But is the damage applied in a single instance, or does the game do smaller amounts of damage a large number of times? For the purposes of this topic, it must be a single damage amount displayed by the game, not multiple damage amounts.

Apologies, this is the only thing i remember. I went through the baldur's gate saga quite some time ago...