Here are the new monsters (and hazards/traps and NPCs) from H1-H3:
Keep on the Shadowfell
Blue Slime (Level 3 Solo Brute)
Nanaran, Elf Archer (Level 4 Artillery)
Sir Keegan (Level 4 Solo Brute)
Balgron the Fat (Level 4 Lurker)
Irontooth (Level 3 Elite Brute)
Dragon Statue (Level 3 Hazard)
The Thing in the Portal (Level 4 Hazard)
Titan Statue (Level 4 Hazard)
Whirlpool Trap (Level 4 Hazard)
Hobgoblin Torturer (Level 3 Brute)
Hobgoblin Warchief (Level 5 Soldier)
Kalarel, Scion of Orcus (Level 8 Elite Controller)
Orcus Underpriest (Level 5 Controller)
Thunderspire Labyrinth
Bronze Warder (Level 7 Elite Soldier)
Surina (Level 5 Skirmisher)
Duergar Guard (Level 4 Soldier)
Duergar Miner (Level 5 Minion)
Duergar Scout (Level 4 Lurker)
Duergar Shock Trooper (Level 6 Brute)
Duergar Theurge (Level 5 Controller)
Enigma of Vecna (Level 6 Controller)
Human Mage of Saruun (Level 12 Controller)
Norker Berserker (Level 4 Elite Brute)
Norker Grunt (Level 3 Minion)
Norker Shadowblade (Level 5 Lurker)
Norker Slinger (Level 3 Artillery)
Norker (Level 3 Soldier)
Brugg (Level 8 Brute)
Phalagar (Level 6 Elite Controller)
Rundarr, Duergar Champion (Level 6 Elite Brute)
Urwol, Master Smith (Level 5 Controller)
Murkelmor (Level 7 Elite Soldier)
Kedhira, Duergar Theurge (Level 5 Controller)
Framarth, Deurgar Theurge (Level 5 Elite Controller)
Maldrick Scarmaker (Level 8 Elite Artillery)
Doom Sphere (Level 5 Obstacle)
Krand, Hobgoblin Chief (Level 5 Soldier)
Arbalester (Level 4 Artillery)
Paldemar (Level 11 Elite Artillery)
Bonecrusher Skeleton (Level 7 Soldier)
Crossbow Turret (Level 3 Blaster)
Draining Mirror (Level 5 Obstacle)
Elemental Vortex (Level 3 Obstacle)
Grasping Dead (Level 3 Obstacle)
Minotaur Bloodtaker Statue (Level 6 Blaster)
Roaring Terror (Level 3 Obstacle)
Teleportation Mirror (Level 5 Obstacle)
Trapping Mirror (Level 5 Obstacle)
Pyramid of Shadows
Arborean Plant Terror (Level 11 Elite Brute)
Arborean Reaper (Level 7 Soldier)
Arborean Speaker (Level 10 Controller (Leader))
Arborean Watcher (Level 7 Lurker)
Eater of Knowledge Mindstrike (Level 8 Elite Controller)
Eater of Knowledge Thoughtbow (Level 7 Artillery)
Eater of Knowledge Voidblade (Level 6 Soldier)
Human Ambusher (Level 7 Skirmisher)
Human Mage (Level 8 Elite Artillery)
Charnel Lord (Unique Otyugh) (Level 10 Elite Soldier)
Charnel Rat (Level 7 Minion)
Gharash Vren (Level 10 Soldier)
Eladrin Blades of Winter (Level 7 Minion)
Eladrin Blizzard Speaker (Level 8 Elite Controller)
Eladrin Winter Knight (Level 7 Soldier (Leader))
Gurrak, Ettin Headtaker (Level 10 Elite Soldier)
False Shard (Level 10 Minion)
Far Realm Abomination (Level 10 Solo)
Boneslider (Level 7 Lurker)
Frigid Aura (Level 3 Obstacle)
Heart of Madness (Level 9 Obstacle)
Prismatic Vortex (Level 10 Obstacle)
Headless Corpse (Level 8 Solo Controller)
Human Archer (Level 7 Artillery)
Human Outlaw (Level 8 Soldier)
Karavakos's Shadow (Level 11 Controller)
Frenzied Werewolf (Level 8 Solo (Brute))
Karavakos (Level 15 Elite Artillery)
Kravak the Damned (Level 10 Elite Controller)
Arat Karavakos (Level 10 Elite Artillery)
Clamping Stairs (Level 7 Obstacle)
Glyph of Ioun (Level 7 Warder)
Grasping Bones (Level 10 Obstacle)
Inferno Room/Teleport Hall (Level 8 Blaster)
Pivoting Floor and Wall (Level 7 Obstacle)
Shifting Stairs (Level 7 Warder)
Stranglemist Death Trap (Level 10 Solo Lurker)
Water Pipe (Level 7 Obstacle)
Frightful Wraith (Level 7 Lurker)