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