CULLED MONSTERS of BX: A ~30 min of effort response to a Twitter post

The below are 40 monsters I think are the most interesting monsters in BX straight from the list. I think oftentimes the best monsters are those you make up yourself, but sometimes I enjoy the exercise of working with specific constraints. For comparison, here is False Machine's Top 10 Emblematic Monsters of D&D. 

1. Ape, White - four-armed scary bear
2. Basilisk- Tomb of the Serpent King & Mork Borg make them cool again
3. Giant Vampire Bat- maybe tackles PCs like a linebacker; sucks blood
4. Oil Beetle- acid; minus HP and AC
5. Tiger Beetle- underground predator
6. Berserker- a better “orc”
7. Caecilia- just feels kinda weird and maybe intelligent
8. Cave Locust- more bizarre “alarm creature”
9. Chimera- always feels fun; just put anything together
10. Giant crocodile- better than a lazy dragon; weirdly will feel more fresh than one
11. Cyclops- a classic and more interesting than giants; bigger too at 13 HD!
12. Doppelgänger- always fun
13. Dragon Turtle- better than a dragon really
14. Driver Ant- weird cave insect
15. Giant Rockfish- fun to put in shallows dungeon lakes
16. Cloud Giant- live in cloud castle, maybe harries earth-bound cyclops for fun
17. Amber Golem- maybe the “armor” of insect sorcerers inside
18. Bronze Golem- molten fire for blood is fun
19. Griffon- don’t see enough, eats horses and hirelings
20. Harpy- also fun
21. Hydra- DRAGON TERATOMA
22. Invisible Stalker- whoever rolled that “sack of flour” as a starting item will be the hero
23. Killer Bee- put them in a temple farmed by monks
24. Crystal Living Statue- something I don’t see a lot; monster AND treasure
25. Devil Swine- these are actually really good; capable shapeshifting, satanic, hypnotizing Ganons
26. Wererats- only “armed” were-creature; better goblins
27. Manticore- talky monster; also flys
28. Medusa- talky monster; threatens the players
29. Minotaur- better as a true cursed human
30. Mummy- not often used undead; hurt by normal flame but did you bring enough
31. Ochre Jelly- divides into smaller jellies, latch onto players
32. Octopus, Giant- awesome since childhood
33. Purple Worm- better dragon
34. Rhagodessa- like the Caecillia; weird cave thing; intelligent; maybe trade hirelings for magic weapons
35. Robber Fly- sounds fun
36. Rust Monster- should be used more, bear sized, destroy weapons
37. Salamander- better than fire elementals
38. Crab Spider- spider things are fun
39. Thoul- 2 for 1 troll and ghoul
40. Wraith- alternative to litch or vampire; AND killed PCs come back!

Special mention: I like all the oozes, puddings, and jellies

LET THERE BE LIGHT: Making Light More On/Off

The Problem: Generally drawing a dungeon map as you go only to the extent of the light source radius is a pain. And other players tracking who has the torch is "meh" as well. Most players don't like to track torches or give up a weapon or shield. The actual benefits of using a torch or lantern are pretty vague in BX as are the detriments of darkness (the below taken from Old School Essentials). 

• Darkness: Characters will usually want to bring a source of light with them on underground expeditions. Typical light sources enable normal vision within a 30’ radius.
• Torch: A torch burns for 1 hour (6 turns), clearly illuminating a 30’ radius. Torches may also be used in combat (melee, 1d4 dmg).
• Light and Surprise: Characters or monsters that carry a light in a dark environment are usually unable to surprise opponents because the light gives their presence away.
• Suprise in BX D&D: 

• Each side that is not already aware of the other’s presence rolls 1d6.
• Monsters: The referee rolls for monsters. PCs: One player rolls for the adventuring party as a whole.
• Results: A result of 1 or 2 means the side is surprised.
• Effects of Surprise: Both sides surprised: There is simply a momentary confusion—neither side has any advantage. One side surprised: The side that is not surprised gains a one round advantage. The surprised side cannot act that round.

I think we can also infer a few other things about sight, light, and darkness from spells and monsters:

• The Light spell: "Blinding a creature: By casting the spell upon its eyes. If the target fails a saving throw versus spells, it is blinded for the duration. A blind creature cannot attack."
• Invisible Stalker: "Surprise: On a 1–5, unless target can detect invisibility."
• Pixie: Invisible: Naturally invisible, but may choose to reveal themselves. May remain invisible when attacking: cannot be attacked in the first round; in subsequent rounds, maybe attacked at –2 to hit.

But anyone whose ever been in a cave, unlit alley, or dark basement knows that the need and desire for light is strong. So I would like to compress the above rules into a sort of toggle: With Light or No Light. This I think makes it easier to judge and incentivizes the PCs to use light sources:

WITH LIGHT

Vision: as normal up to the strongest light radius

Search: +1 in 6

Suprise: on 2 in 6; can't surprise others

Encounter: begins at the radius

Combat: as normal up the radius

WITHOUT LIGHT

Vision: vague impressions, large features

Search: impossible

Suprise: on 5 in 6; can surprise others

Encounter: begins at 1d6 (1-2 10', 3-4 20', 5-6 30')

Combat: cannot attack only grapple (or maybe -4 to-hit)

EXCESS LIGHT

1 Light source results in the above

50% of the party has light, surprise 1 in 6

75% of the party has light, initiative +1

DAVID WESELY: The Godfather of RPGs

Finches by Chuck Darwin

Despite what you read on the internet, D&D was NOT birthed from a wargame*. D&D arose when Gary Gygax was invited to a game Dave Arneson's Blackmoor which was a spin-off of David Wesley's Braunstein game.

Here is an old post from Pits Perilous who interviewed Wesley about the Braunstein game. Which is a great companion piece to the documentary The Secrets of Blackmoor and the book, Playing at the World.

* Its combat system certainly was, but not the idea of roleplaying individuals delving a dungeon under a castle. You switch any skirmish-size combat system into D&D and it will still feel like D&D.