In both Labyrinth Lord and basic D&D, dragons appear in the monster section of each rulebook. Dragons are an extremely nasty monster, even for experienced players. Can you even use them against a low level (1-3) party?
The weakest dragon type is a white dragon. Here is a quick refresher on its stats:
AC: 3 HD: 6 D: 1-4/1-4/2-16
Let's start with hit points. If the expected value of a 1d8 is 4.5, the average white dragon will have 27 hp. That hp amount is not out of bounds for a party of 6-8 well-armed 1 level players (q.v. the orge or minatuar in the Keep on the Borderlands). Three attacks per round isn't, by itself, a show stopper for beginning characters. Carrion crawlers/Carcass Scavengers get 8 attacks per round. However, the bite of a white dragon is pretty vicious with an expected value of 9hp. That's a death sentence for all classes by very harty dwarves and fighters.
But we haven't gotten to the really terror of dragons: their breath weapons.
If you have forgotten (and readers of this blog almost certainly have not), dragon breath weapons cause as much damage as the creature's remaining hit points. Even those that make their saving throws will take half that damage. If this weren't enough, note that breath weapon attacks are area attacks, that is, one attack affects everyone with a certain area. Yikes!
The Moldvay rules explicitly state that all dragons will use their breath weapon as their first attack! So, our average white dragon will spew a 80'x30' cone of frosty death for 27 hp of damage on the first round it attacks. Against our first level party, none of the affected PCs will survive. No first level character can have more than 11 hp. Assuming every PC saves, the breath weapon charitably does 13 points of damage.
Total party kill, indeed.
But there is an out: dragon age.
The Moldvay rules state that the dragon stats given are merely average values. Young dragons will have 3 fewer HD, while older ones have 3 more HD.
So the young white dragon will have 3 HD and, on average, 12-15 hp.
Now the breath weapon is slightly more survivalable. The 12 hp version of the draon will still kill all players who fail their save and most of the non-fighters who make theirs. That's pretty grim! But what is perhaps worse is that the drgaon still have vicious claw/claw/bite attacks. These attacks are not affected by age.
Our young dragon's bite IS worse than its bark/breath.
So should low adventures include dragons? I wouldn't rule them out. The Lake Geneva boys knew that dragons would be a challenge for new players. However, I can't think of a better "end boss" for a campaign. I suggest dragons would make a poor choice for wandering monsters though.