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