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