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