Here is the full list of all 66 Torchlight achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Retire over 300 levels worth of characters
Defeat Ordrak on Normal Hardcore
Kill 50,000 monsters
Complete 50 Hatch Quests
Achieved enlightenment by speaking with the horse 100 times
Defeat Ordrak on Easy Hardcore
Catch 1000 fish
Complete 200 Quests
Beat the game with all three classes
Defeat Ordrak on Hard Hardcore
Drink 5,000 potions
Sell 10,000 items to vendors
Retire two characters
Die 500 times
Reach level 100
Smash 1500 Breakables
Reach the 50th floor of a dungeon
Achieve maximum fame
Complete 25 Gar Quests
Retire a character
Achieve player level 100
Kill 25 champion trolls
Suffer 20 disenchants from the enchanter
Gamble 100 times
Achieve player level 65
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
Do at least 10,000 damage to an enemy in a single strike
Defeat Ordrak on Easy or Normal
Defeat Alric
Catch 100 fish
Gamble 50 times
Collect 250,000 gold
Gamble 20 times
Have 100,000 gold in your inventory
Defeat Medea
Kill 5000 Monsters
Defeat Krag
Gamble a unique item
Use 50 potions on your pet
Defeat the Ember Colossus
Catch 50 fish
Take 25,000 steps
Defeat the Root Golem
Permanently transform your pet
Successfully enchant one item 10 times
Pull 100 levers
Successfully create 25 items using the transmuter
Have an item disenchanted on the first enchantment attempt
Defeat the Overseer
Successfully enchant one item 5 times
10 mods used at the same time
Transform your pet into a Mimic
5 mods installed at the same time
Equip a spell on your pet
Defeat Brink
Change your pet by feeding it fish
Fill your pet's inventory
1 game mod installed
Blow 25 enemies to pieces with critical strikes
Send your pet to town
Find the entrance to the mine