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