So, I wanted a way to compare the strengths of monsters in Hero Quest. What I came up with was a number for each monster, which I call the monster's "slaying cost". This number reflects the average amount of damage a hero in Hero Quest would take in a fight before the monster is killed. The higher the number, the tougher the monster. Two monsters with different stats but with equal slaying costs, would be equally tough to kill.
In order to calculate this number, I needed the stats of an "average hero". Looking at the stats of the four heroes, it was easy to see that 2 dice in attack and 2 in defence were a good choice. To keep things simple, I calculated with only this "average hero" fighting the monster without extra equipment or spells.
Calculation was done by a computer program I made where you input attack and defend dice for hero and monster, as well as the amount of body points the monster has. Then the program simulates 10 million fights (some hero would get a tired arm

For my choice of "average hero" above, here are some slaying costs I calculated:
Goblin 0.6
Orc 1.3
Fimir (UK) 1.4
Fimir (US) 2.9
Skeleton 0.7
Zombie 0.8
Mummy (UK) 1.7
Chaos Warrior (UK) 1.7
Gargoyle (UK) 2.4
Gargoyle (US) 8.4
Stone Chaos Warrior (UK) 1.9
Ulag the Orc Warlord (UK) 2.8
Grak (UK) 2.4
Skaven Warrior (WD134) 0.7
Rat Ogre (WD134) 1.4
Troll (WD134) 1.7
Ogre Chieftain (WD145) 16.2
Now having these numbers allow for some fun. I've used them for judging how much of a threat (monster-wise) the different quests are compared to each other. Below you see a list of the main UK quests and their total sum of monster slaying costs. Just remember that any magic abilities of special monsters are not counted, so a bit of adjustment might be recommended. Also, traps do not impact these numbers.
The Maze (7.8)
Melar's Maze (12.4)
The Rescue of Sir Ragnar (13.5)
The Stone Hunter (16.0)
The Fire Mage (17.2)
Prince Magnus' Gold (17.3)
Lair of the Orc Warlord (17.7)
Race Against Time (18.4)
Castle of Mystery (21.1)
Legacy of the Orc Warlord (21.9)
Barak Tor - Barrow of the Witch Lord (14.2)
Quest for the Spirit Blade (21.3)
Return to Barak Tor (23.0)
Bastion of Chaos (27.1)
The Trial (30.0)
This just confirmed what I suspected: that "The Trial" is tougghhhhh. To me, it really should be the last of the main quests, but that would require a mod to its story I guess. Curiously, it also was the last of the main quests to be written, as it didn't appear in the first version of HQ.
Another interesting use for the slaying cost of a monster would be to multiply the number by ten, and have that be the amount of experience a hero gains by killing that monster. Personally tho, I'm not sure I wanna complicate the game by adding XP.
Thought this might be of interest to you fellow HQ'ers.