Here is the full list of all 66 Torchlight achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Sell 10,000 items to vendors
Complete 50 Hatch Quests
Drink 5,000 potions
Catch 1000 fish
Defeat Ordrak on Easy Hardcore
Reach level 100
Reach the 50th floor of a dungeon
Kill 25 champion trolls
Defeat Ordrak on Normal Hardcore
Kill 50,000 monsters
Retire over 300 levels worth of characters
Die 500 times
Suffer 20 disenchants from the enchanter
Catch 100 fish
Have an item disenchanted on the first enchantment attempt
Defeat Ordrak on Hard Hardcore
Achieve player level 100
Achieve maximum fame
Transform your pet into a Mimic
Achieved enlightenment by speaking with the horse 100 times
Defeat Ordrak on Very Hard Hardcore
Complete 200 Quests
Retire two characters
Retire a character
Smash 1500 Breakables
Catch 50 fish
Defeat Ordrak on Hard
Defeat Ordrak on Very Hard
Defeat Ordrak in 8 hours or less
Defeat Ordrak in less than 5 hours
Defeat the Overseer
Defeat Brink
Permanently transform your pet
Beat the game with all three classes
Complete 25 Gar Quests
Successfully create 25 items using the transmuter
Use 50 potions on your pet
Gamble 100 times
Gamble 50 times
Achieve player level 65
Gamble 20 times
Collect 250,000 gold
Successfully enchant one item 10 times
Successfully enchant one item 5 times
Take 25,000 steps
Defeat Ordrak with no deaths
Defeat Ordrak on Easy or Normal
Defeat Alric
Pull 100 levers
Kill 5000 Monsters
Change your pet by feeding it fish
Send your pet to town
Equip a spell on your pet
Gamble a unique item
10 mods used at the same time
Defeat Medea
Have 100,000 gold in your inventory
Defeat Krag
Defeat the Ember Colossus
Defeat the Root Golem
Do at least 10,000 damage to an enemy in a single strike
Blow 25 enemies to pieces with critical strikes
Find the entrance to the mine
Fill your pet's inventory
1 game mod installed
5 mods installed at the same time