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