Dragon Encounters

Spellcaster

Dryad (CR 1)

Druid (CR 2)

Drider (CR 6)

Pit Fiend (CR 20)

Glabrezu (CR 9)

Barlgura (CR 5)

Spectator (CR 3)

Planetar (CR 16)

Duergar (CR 1)

Drow Mage part 1: (CR 7)

Skirmisher

Young White Dragon (CR 6)

Displacer Beast (CR 3) Both independent and as a minion

Imp (CR 1)

Chasme (CR 6)

Behir (CR 11)

Incorporeal

Shadow Demon (CR 4)

Banshee (CR 4)

Ranged

Drider (CR 6)

Young Blue Dragon (CR 9)

Horned Devil (CR 11)

Vrock (CR 6) (Note: as one of the few monsters in D&D with ongoing damage effects, the vrock has a somewhat unique combat style)

Cyclops (CR 6) Poor aim, but deadly area effects (see article)

Centaur (CR 2)

Needle Blight (CR 1/4)

Solar (CR 21)

Ambusher

Dragon Turtle (CR 17)

Young White Dragon (CR 6)

Quasit (CR 1) Also used to spy of PCs, and similar stealth tactics

Cloaker (CR 8)

Bullywug (CR  1/4)

Rug of Smothering (CR 2)

Drow Elite Warrior (CR 5)

Suprise Attack

Shadow Dragon (CR 17)

Young White Dragon (CR 6)

Young Blue Dragon (CR 9)

Bullete (CR 5)

Bugbear (CR 1)

Twig Blight (CR 1/8)

Brute

Young Red Dragon (CR 10)

Hezrou (CR 8)

Chimera (CR 6)

Grappler

Drider (CR 6)

Young Blue Dragon (CR 9)

Maralith (CR 16) (More tank than grappler. Locks down PCs instead of moving them.)

Chasme (CR 6)

Vine Blight (CR 1/2)

Forced Movement

Air elemental (CR 5)

Reverse Grappler

Barbed Devil (CR 5)

Boss Monster Tactics

Demilich (CR 18)

Lair Actions

Ancient Gold Dragon (CR 24)

Flyby

Pteranodon (CR 1/4)

Unique Abilities

Young Gold Dragon (CR 9)

Ice Devil (CR 14)

Chain Devil (CR 8)

Bone Devil (CR 9)

Bearded Devil (CR 3)

Dretch (CR 1/4)

Basilisk (CR 3)

Earth Elemental (CR 5)

Water Elemental (CR 5) Unstoppable Movement

Heist Obstacles

Adult Gold Dragon (CR 17)

Rug of Smothering (CR 2)

Animated Armor (CR 1)