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