Here is the full list of all 119 Torchlight II achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Use 5,000 potions
Deal 100,000 critical strikes
Reach level 100
Obtain a tier 3 skill bonus
Find a legendary item
Recover 100 gems from items
Have 1,000,000 gold
Break 10,000 breakables
Use 10 maps
Defeat the Nether King as a Berserker
Defeat the Nether King in Veteran difficulty
Assemble TrillBot
Die with a hardcore character
Fish 100 times
Defeat the Nether King as an Engineer
Squish 1000 critters
Defeat Boletus Rex
Start a hardcore character
Have 100,000 gold
Sell 5,000 items
Defeat 500 champions
Find 10 secret rooms
Socket 50 gems into items
Squish 500 critters
Wear a completed armor set
Trade an item with another player
Join a multiplayer game
Explode 10,000 enemies
Use an enchanter 50 times
Take 100,000 steps
Use a map
Begin new game plus
Defeat the Nether King in Casual difficulty
Defeat the Nether King in Normal difficulty
Defeat the Nether King as an Outlander
Defeat the Nether King
Defeat the Dark Alchemist
Defeat Vyrax
Deal 10,000 critical strikes
Recover 10 gems from items
Add a friend
Start a multiplayer game
Defeat Verona
Defeat Marishka
Defeat Aleera
Defeat Killbot
Use 500 potions
Defeat Thiss
Do 10,000 damage with a single attack
Defeat Cacklespit
Defeat the Wraith Lord
Defeat Bloatfang
Defeat the Grizzled Alpha
Obtain a tier 2 skill bonus
Take 50,000 steps
Defeat the King In Masks
Defeat the Siege Guardian
Defeat Ezrek Khan
Learn 4 spells
Defeat Aruk
Teach a pet 4 spells
Open 500 chests
Defeat the Artificer
Defeat the Manticore's Mate
Defeat the Manticore
Squish 100 critters
Break 1,000 breakables
Recover a gem from an item
Defeat 100 champions
Deal 1,000 critical strikes
Defeat Grand Regent Eldrayn
Use 50 potions
Sell 500 items
Defeat Kidrik the Mauler
Destroy a socketed gem
Teach a pet a spell
Learn a spell
Use an enchanter 10 times
Explode 1,000 enemies
Defeat Chillhoof
Take 10,000 steps
Defeat King Pogg
Defeat 25 champions
Open 100 chests
Defeat the Winter Widow
Defeat Mordrox
Defeat One-Eyed Willy
Defeat General Grell
Obtain a tier 1 skill bonus
Find a secret room
Break 100 breakables
Fish 10 times
Socket a gem into an item
Defeat the Fallen Guardian
Send your pet to town
Open 20 chests
Explode 100 enemies
Defeat the Nether King with each of the 4 classes
Defeat the Nether King in Elite difficulty
Defeat the Nether King as an Embermage
Defeat the Nether King in hardcore mode (casual)
Defeat the Nether King in hardcore mode (elite)
Defeat the Nether King in hardcore mode (normal)
Defeat the Nether King in hardcore mode (veteran)
Fish using dynamite
Use an enchanter 500 times
Fish 1,000 times
Have 10 friends
Have 50 friends
Purchase 20 items from the gambler
Purchase 50 items from the gambler
Purchase 100 items from the gambler
Have 10,000,000 gold
Destroy 10 socketed gems
Destroy 100 socketed gems
Find 100 secret rooms
Sell 50,000 items
Socket 500 gems into items
Use 100 maps