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