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