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