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