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