Lizard: There are four types of lizards detailed here: Fire, Giant, Minotaur and Subterranean.
Fire lizards first appeared in Supplement II. Their Armor Class has worsened from 2 to 3, and their Hit Dice has been lowered from 12 to 10. Their breath weapon has now been given a specific range and area of effect, and the damage has changed from 1-10 to 2-12. Somewhat uncharacteristically, Gary seems to have dropped a lot of the detail that this monster previously had, such as lifespan and the length of their periodic hibernations. He’s replaced it with a market value for their eggs, though, which is very characteristic.
Giant lizards were first mentioned in the wilderness encounter tables from Supplement III. There was also an entry for plain old lizards in OD&D Vol. 3, which I assume to be the same monster (if not, that's one hell of an uneventful random encounter). This is the first time they get stats. I assumed they’d just be a generic low-level monster, and they are for the most part, but they do have the specific ability to do double damage when they roll a natural 20 to attack. It’s a pretty common house rule to apply this to everybody, but if you do that it deprives this monster of its only special ability. Unless you let them do triple or even quadruple damage, which could get a touch absurd.
Minotaur lizards first appeared in Supplement II. Their Armor Class has worsened from 3 to 5, their movement has slowed from 9” to 6”, and their damage ranges have been seriously nerfed. Whereas before they had a claw/claw/bite routine dealing a whopping 2-20/2-20/4-32, they now do a much more reasonable 2-12/2-12/3-18. In exchange for their weakened stats, they’ve gotten better at gaining surprise, and on an attack roll of natural 20 they can pick up their opponent and automatically bite again on the next round.
Subterranean lizards make their first appearance here. Like giant lizards they get the double damage on a natural 20, and they can run along walls and ceilings with ease. They're also a fair bit tougher than regular giant lizards, but they sort of have to be to survive underground in a D&D world.
Lizard Man: These guys first appeared in Supplement I. Their stats remain mostly the same, with only their claw damage reducing from 1-3 to 1-2. Even their description has barely changed. The only thing that is new is that a distinction has been made between primitive lizard men (those that use their natural weapons) and advanced ones (those that use weapons like darts, javelins and clubs).
Locathah: Locathah are a race of nomadic fish men that first appeared in Supplement II. Pretty much all of their stats have changed: Armor Class from 7 to 6; Movement Rate from 24 to 12; Hit Dice from 2+1 to 2; and Number Appearing from 30-300 to 20-200. The latter suggests that some sort of disaster has decimated the locathah population, which I might work in somewhere. There are numerous additions in their description as well. They’re still nomads that ride eels, which I think is rad. Their numbers have now also been bolstered with the possibility of some mid-level fighters. Their favoured weapons are now revealed as lances, tridents, crossbows and nets. Despite being nomadic, they are said to live in huge rocks that have been hollowed out with rooms and passages.
I was going to try and finish the letter L today, but I didn’t count on Lycanthropes and Lizards with their multiple entries. Next time!