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