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