Here is the full list of all 66 Torchlight achievements. It takes around 100-120 hours to unlock all of the achievements on Windows.
Complete 50 Hatch Quests
Die 500 times
Sell 10,000 items to vendors
Kill 50,000 monsters
Drink 5,000 potions
Catch 1000 fish
Defeat Ordrak on Very Hard
Defeat Ordrak on Very Hard Hardcore
Defeat Ordrak on Hard
Defeat Ordrak on Hard Hardcore
Retire two characters
Retire over 300 levels worth of characters
Defeat Ordrak on Normal Hardcore
Achieve player level 100
Reach level 100
Reach the 50th floor of a dungeon
Smash 1500 Breakables
Beat the game with all three classes
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
Do at least 10,000 damage to an enemy in a single strike
Kill 25 champion trolls
Complete 200 Quests
Complete 25 Gar Quests
Gamble 100 times
Gamble 50 times
Suffer 20 disenchants from the enchanter
Achieve maximum fame
Successfully enchant one item 10 times
Achieve player level 65
Gamble 20 times
Have 100,000 gold in your inventory
Use 50 potions on your pet
Collect 250,000 gold
Defeat Ordrak on Easy or Normal
Defeat Alric
Achieved enlightenment by speaking with the horse 100 times
Defeat Medea
Transform your pet into a Mimic
Kill 5000 Monsters
Defeat Krag
Gamble a unique item
Defeat the Ember Colossus
Take 25,000 steps
Successfully enchant one item 5 times
1 game mod installed
5 mods installed at the same time
10 mods used at the same time
Pull 100 levers
Defeat the Root Golem
Successfully create 25 items using the transmuter
Have an item disenchanted on the first enchantment attempt
Catch 100 fish
Defeat the Overseer
Permanently transform your pet
Catch 50 fish
Change your pet by feeding it fish
Fill your pet's inventory
Equip a spell on your pet
Defeat Brink
Blow 25 enemies to pieces with critical strikes
Send your pet to town
Find the entrance to the mine