A first level PC took 144 points in one hit...
Well, this might not be the most, but I bet it is close to the most for a first level PC in regards to damage taken in one hit.
But, back in 2E days, before d20 laws, we used an unofficial non-D&D supplement for critical hits. It was pretty good and was not too egregious, but it had some wild damage modifiers if you rolled the right number. Most rolls on the chart did not result in more than double damage, however. We make all of our to hit and damage rolls on the table as well – DM included.
First off, we played that a natural 20 was automatic double damage and you then consult the critical hit chart. So, when a first level PC blundered about looking for something in a dark cave (and blunder is the right word) – a wolf leaped out and bit him. The DM rolled a 20 to hit, so double damage. I forget the damage by the bite, but it was either 2d4 or 1d8. But, nonetheless, the DM got max damage there for 8 points. That is doubled due to the 20 to 16 points. The DM then rolled on the critical hit chart (again, in the open) and got the dreaded "00" roll... head severed at neck, 9x damage modifier. So, it was 144 points of damage delivered to a first level PC with one hit.
Needless to say, that PC died.