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