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