Lots of changes have happened in DnD 5th edition since the publication of the first Monster Manual. The argument could easily be made that Mordenkainen Presents: Monsters of the Multiverse is a better source for monster in your game. The Stat Blocks in Mordenkainen’s are simplified for ease of use, and the monsters’ abilities are more in line with the power creep of player characters.
That said, there are so many iconic monsters in the Monster Manual, that I still think it’s a great source for your game, even when slightly newer books like Volo’s Guide to Monsters, have been heavily republished and seem deprecated. Many of D&D’s truly iconic monsters live there: Aboleths, Beholders, Mind Flayers, and Tarrasques to name a few. There are also a bunch of lesser known but equally great monsters as well.
Lesser Icons of the Monster Manual
Animated armor are great monster for blending into the set dressings of a medieval castle. While they are motionless, PCs cannot identify them as being anything other than a normal suit of armor. They have blindsight, which will help them detect the sneakier members of the party. They can also be commanded by their creators to request passwords and say scary stuff and deliver riddles.
With a 1 in Intellligence, though, they’re not strong thinkers, so you cleverer PCs can find ways to confuse or manipulate them. If you need something a little beefier and smarter to throw at your players, consider a Helmed Horror. These are a stronger version of animated armor designed for messing up the day of a spellcaseter.
These aberrations were left behind by Aboleth (see above). They are giant bugs, which always scores points for “ick” factor in roleplay. They are a tentacle situation, which is also another point in the favor. At least it is in my book. The tentacles extend from their faces and can be used to poison and paralyze creatures they are grappling. These are very dangerous low-level monsters as they can easily remove a PC from combat early.
These monsters were created to collect magic items for their Aboleth master, and to server as guardians. Players who come across them will likely attract their attention if they have any magical items or abilities. They’re also likely to find something taht was valuable to the old masters being guarded by one of these creatures. I’ve also had a lot of fun in the past reskinning them as giant lobsters, even though they’re a few legs short.
Here I go again, betraying my deep love for all things insectile. Remorhazes have so many legs, how can players not hate them? That’s just the start though. They have heated bodies that punish melee attacks against them with fire damage. They can swallow creatures that they have grappled with their bite attack. Not to mention, the 20 ft. burrow speed lets them attack from and retreat to subterranean safety.
There is also a stat block for Young Remorhaz. I’ve created whole colonies of remorhaz using reskinned Kruthik or Ankheg. The Remorhaz stat block serves as the queen. Young Remorhaz can be drones. Fill in the different types of juveniles with re-skinned crabby/buggy monsters of your choice.
More than a few other monsters from the original Monster Manual have made it onto my Hotlist. Check ’em out!