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