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