D&D General Monsters you love to hate, and monsters you hate to love.

[Levistus's_Leviathan]

The only gotcha monsters I like are mimics... who are bad at what they're doing.

I don't know about that. Mimics are fine . . . against newer players. Same with the other classics like Gelatinous Cubes.

But anyone that knows anything about D&D will probably not fall for them. Just like they'll know a Troll's weaknesses are acid and fire and that shiny dragons are good and rainbow dragons are bad.

 

[Levistus's_Leviathan]

And recently acquired a new toy by commission: a shotgun sized to be mounted on his tail. Which is to say a repeater cannon loaded with grapeshot.

I know it's a different type of gun, but I'm reminded of Rattlesnake-Jake from Rango.

 

[RoughCoronet0]

The only gotcha monsters I like are mimics... who are bad at what they're doing.

Funnily enough, my group loves when a mimic is encountered. Not because they are good enemies, but because it’s become a tradition to befriend the mimic and make them quirky traveling companions.

Randy the savvy Mimic is one of the most iconic NPCs from my group’s long campaign history.

 

[CleverNickName]

This does bring up a big pet peeve, monsters I truly despise. "Gotcha" monsters. Things that are either perfect at pretending to be other things, or things that have special abilities that there is no way to avoid without knowing what you're up against in advance.

Oh you would absolutely hate playing at my table!

All of the dragons in my campaign are normally greenish-gray, and they have the chameleon-like ability to change the color of their scales to match their surroundings. No easy way to tell what breath weapon the wyrm is going to use, and that rock outcrop might actually be a dragon blending in...

If an enemy spellcaster is powerful enough to know Disguise Self, it will use it. Same for Polymorph. It never made sense to me that a monster or NPC could be intelligent enough to use magic, and not...you know...use it...

Very few of my combat scenes start out with a clear idea of what the players are up against, or even how many opponents they might be facing when we roll initiative.

 

[DrunkonDuty]

Please do not disparage the fine names of greed and alcoholism.

I agree!

 

[James Gasik]

Oh you would absolutely hate playing at my table!

All of the dragons in my campaign are normally greenish-gray, and they have the chameleon-like ability to change the color of their scales to match their surroundings. No easy way to tell what breath weapon the wyrm is going to use, and that rock outcrop might actually be a dragon blending in...

If an enemy spellcaster is powerful enough to know Disguise Self, it will use it. Same for Polymorph. It never made sense to me that a monster or NPC could be intelligent enough to use magic, and not...you know...use it...

Very few of my combat scenes start out with a clear idea of what the players are up against, or even how many opponents they might be facing when we roll initiative.

Huh. And you don't find that this prevents players from being prepared or to make good strategic choices?

 

[Vaalingrade]

I don't know about that. Mimics are fine . . . against newer players. Same with the other classics like Gelatinous Cubes.

But anyone that knows anything about D&D will probably not fall for them. Just like they'll know a Troll's weaknesses are acid and fire and that shiny dragons are good and rainbow dragons are bad.

That's why I use them for fun instead of as traps.

All trap monsters have a limited shelf life as a 'lol, look at you stupid players getting tricked by me, the awesome, smart and handsome DM' effect.

 

[WarDriveWorley]

As a player I hate (HATE) Sons(spawn) of Kyuss. Back in the day when I first started playing D&D I lost a favorite ranger to an encounter with these due to our hireling being infected and attacking me from behind then turning me too. It freaked me out and I still get chills thinking of it.

As a DM I love owlbears, Dragons (as antagonists, not just giant siege engines), Rust Monsters, Umber Hulks, and anything with casting abilities since I always change up the spells they have.

 

[EzekielRaiden]

Mindflayers.

My players have fought exactly one mindflayer. They really, really learned to hate mindflayers after that fight. Even though they won! Sort of. (They won because they freed the couatl he was trying to corrupt; she was still partially corrupted, but her first instinct was to kill the mindflayer, not the people. They were able to restore her afterward, and she's now a distant ally.)

 

[James Gasik]

Any monster that can turn you into a monster is pretty bad, but the worst are things like lycanthropes, who do it without actually killing you. I mean, what is even the point here? "Oh sorry Jane, you're a werewolf now, that means you're an NPC because otherwise you'd be overpowered for having the nerve to get bit by a werewolf...".

Actually, on the topic of werethings, creatures that are only scary if you have no idea what they are/not prepared to fight one. There's this whole metagame thing about "you don't know troll regeneration can be stopped by fire" that makes my eye twitch every time it comes up.

Things aren't so bad these days, but back when werewolves were either a cakewalk or a TPK based on whether or not you had silver weapons always made me wonder what they were for- either you can fight it and it's a joke, or you can't and it infects the whole party?

Low CR monsters that can murder unprepared adventurers in general. 5e has made some things less obnoxious (like ghouls, thank Gygax), but the Shadow is still able to obliterate anything with an AC of 16 or less. Only 16 hp? Look again, they are at least resistant to just about anything you can hit them with! And if you're Strength-based melee, one hit can render you into a helpless bag of hp, unable to even wear your heavy armor! Not that they care about hp, because they can kill you even if you have a thousand hit points!