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