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