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