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