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