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