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