Favorite Monster (Aberration)
Aboleth. They’re very similar to illithids, but not humanoids. I also enjoy their aberrant ability to suffocate creatures with their strange mucus ability. Since aboleths are aquatic and majorly into taking thralls they need creatures able to breathe underwater. They do this by an ability that changes a creature’s skin into a permeable layer used for respiration in water. So a PC who is not dominated by the aboleth could still suffocate without realizing they have to be in the water to breathe.
Their ability to basically live forever and their awesome racial memory coupled with stealing the knowledge of thralls means they can basically hang out anywhere so long as there is some pooled water. Cool creatures and they make great head villains.
Favorite Monster (Animal/Vermin)
Swarms. There is just something iconic about swarms, a horde of small creatures overwhelming someone. Individually the creatures are nothing more than a nuisance worthy of swatting or ignoring; snakes, spiders, ants, rats, bats, bees. But frenzied en masse they can swell over adventurers like a living wave. It is even better if they’re the sort of swarm that can occupy the same physical space as their target making them more difficult to hit and giving missed attacks the chance to hit an ally.
Favorite Monster (Immortal/Outsider)
Githzerai/Githyanki. Cousin races that roam the planes after revolting against their Illithid overlords. I think I like them most because of how human they seem and the juxtaposition of the ‘cousin’ races and how their society formed after winning their freedom from slavery under the mind flayers.
It’s also nice to have an outsider race that is not immediately hostile to adventurers. Xenophobic for sure, but the ability to have a base of operations for planes-hopping adventures is appreciable.
Favorite Monster (Elemental/Plant)
Carnivorous Plants. Use them a lot, especially if I’m going for a Man vs. Nature or Civilization vs. Wilderness theme. There are a lot so it is difficult to narrow the array down to one creature. I would also slip Ropers into this category. Basically I enjoy any monster that can be easily mistaken for scenery. Mimics don’t really fit into this category as artificial items immediately draw attention from the party. But scenery mimicry has been in my experience the best way to create ambush situations.
Favorite Monster (Humanoid/Natural/Fey)
This one is really difficult to narrow down as Humanoid covers a significant chunk of D&D’s back catalog of fiends and monsters. I could choose something very cool but not well known monster like Barghests, or the often overlooked PC races Dwarves, Elves, and Humans. I think in the end I choose shapeshifters. Be it Changelings, Lycanthropy, Barghest, or a Hag I enjoy that there is something about them that is below the surface; something not obvious on initial perception.