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