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