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