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