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