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
Catch 1000 fish
Die 500 times
Sell 10,000 items to vendors
Reach level 100
Kill 25 champion trolls
Drink 5,000 potions
Achieve maximum fame
Achieve player level 100
Achieve player level 65
Do at least 10,000 damage to an enemy in a single strike
Gamble 100 times
Complete 50 Hatch Quests
Reach the 50th floor of a dungeon
Defeat Ordrak on Hard Hardcore
Gamble 50 times
Suffer 20 disenchants from the enchanter
Defeat Ordrak on Normal Hardcore
Have 100,000 gold in your inventory
Kill 50,000 monsters
Beat the game with all three classes
Retire two characters
Successfully enchant one item 10 times
Defeat Ordrak on Easy Hardcore
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 Very Hard Hardcore
Gamble a unique item
Gamble 20 times
Complete 200 Quests
Complete 25 Gar Quests
Smash 1500 Breakables
Use 50 potions on your pet
Catch 100 fish
5 mods installed at the same time
10 mods used at the same time
Collect 250,000 gold
Defeat Ordrak on Easy or Normal
Defeat Ordrak on Hard
Defeat Ordrak on Very Hard
Defeat Alric
1 game mod installed
Defeat Medea
Catch 50 fish
Permanently transform your pet
Defeat Krag
Transform your pet into a Mimic
Successfully create 25 items using the transmuter
Defeat the Ember Colossus
Kill 5000 Monsters
Take 25,000 steps
Defeat the Root Golem
Have an item disenchanted on the first enchantment attempt
Achieved enlightenment by speaking with the horse 100 times
Pull 100 levers
Defeat the Overseer
Equip a spell on your pet
Successfully enchant one item 5 times
Fill your pet's inventory
Change your pet by feeding it fish
Defeat Brink
Blow 25 enemies to pieces with critical strikes
Send your pet to town
Find the entrance to the mine