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