OK, here is the list of monsters I need for achievements:
Rares
Act 1:
Complete
Act 2:
Dust Imp - The Storm Halls,The Unknown Depths
Sand Dweller - Desolate Sands
Skeletal Sentry - Sewers of Caldeum,The Forgotten Ruins
Skeletal Raider - Sewers of Cladeum
Act 3:
Skeletal Marauder - Battlefield Strores
Act 4:
Mallet Lord - The Silver Spire 1/2
Armaddon - Gardens of Hope 1/2,The Silver Spire 1
Champions
Act 1:
Complete
Act 2:
Skeletal Raider - Sewers of Cladeum
Act 3:
Skeletal Marauder - Battlefield Strores
Act 4:
Armored Destroyer - Gardens of Hope 1
Mallet Lord - The Silver Spire 1/2
Subjugator Gardens of Hope 1,The Silver Spire 1
Unique Monsters
Act 1:
Ebenezer Samuel - Old Tristram Road
Merrium Skullthorn - Cathedral Level 2
Captin Cage - Cathedral Level 4
Dreadclaw the Leaper - Fields of Misery
Qurash the Reviled - Caverns of Araneae
Ratlin the Widowmaker - Caverns of Araneae
Zhelobb the Venomous - Caverns of Araneae
Lorzak the Powerful - Southern Highlands
Red Rock - Southern Highlands
Jezeb the Conjurer - Leoric's Manor
Act 2:
Saha the Slasher - Howling Plateau
Gart the Mad - Howling Plateau
Ashek - Black Canyon Mines
Yeth - Road to Alcarnus
Shondar the Invoker - Alcarnus
Hazzor the Viper - Sewers of Caldeum
Torsar - Dahlgur Oasis
Stinging Death Swarm - Eastern Channel
Yakara - Eastern Channel
Blarg the Imp - Desolate Sands
Bloodfeather - Desolate Sands
Hellscream - The Unknown Depths
Mage Lord Ghuyan - The Storm Halls
Act 3:
Growlfang - Skycrown Battlements
Captain Dale - The Keep Depths Level 1
Thornback - The Keep Depths Level 1
Axegrave the Executioner - The Keep Depths Level 2
Belagg Pierceflesh - The Keep Depths Level 3
Dreadgrasp - The Battlefields
Mehshak the Abomination - The Battlefields
Direclaw the Demonflyer - Rakkis Crossing
Lummock the Brute - Rakkis Crossing
Shadra'Har - Rakkis Crossing
Severclaw Arreat Crater Level 1
Demonika the Wicked - Tower of the Damned Level 1
Gholash - Tower of the Damned Level 1
Riplash - Tower of the Damned Level 2
Haxxor - Tower of the Cursed Level 2
Act 4:
Veshan the Fierce - Gardens of Hope Tier 1
Torchlighter - Gardens of Hope Tier 2
Kysindra the Wretched - The Silver Spire Level 1
Pyres the Damned - The Silver Spire Level 1
Slarg the Behemoth - The Silver Spire Level 1
Grimnight the Soulless - The Silver Spire Level 2
Haures - The Silver Spire Level 2
Rhau'Kye - The Silver Spire Level 2
Sao'Thall - The Silver Spire Level 2
I will pay 100k each if it ticks.
Adrenaline#1529 - Offline
Some Champions and Rares are bugged:
http://us.battle.net/d3/en/forum/topic/6246995440#10