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