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