Here is the full list of all 119 Torchlight II achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Fish 1,000 times
Deal 100,000 critical strikes
Sell 50,000 items
Use 100 maps
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 as a Berserker
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)
Use 5,000 potions
Have 10,000,000 gold
Sell 5,000 items
Find a legendary item
Socket 500 gems into items
Defeat the Nether King in Elite difficulty
Defeat the Nether King in Normal difficulty
Defeat the Nether King in Veteran difficulty
Reach level 100
Obtain a tier 3 skill bonus
Defeat 500 champions
Destroy 100 socketed gems
Use an enchanter 500 times
Use 10 maps
Squish 1000 critters
Defeat Aleera
Defeat Verona
Defeat Marishka
Assemble TrillBot
Defeat the Wraith Lord
Find 10 secret rooms
Fish 100 times
Deal 10,000 critical strikes
Have 1,000,000 gold
Purchase 100 items from the gambler
Purchase 50 items from the gambler
Recover 100 gems from items
Purchase 20 items from the gambler
Have 100,000 gold
Destroy 10 socketed gems
Teach a pet 4 spells
Explode 10,000 enemies
Do 10,000 damage with a single attack
Take 100,000 steps
Break 1,000 breakables
Die with a hardcore character
Start a hardcore character
Squish 500 critters
Use 500 potions
Open 500 chests
Use a map
Have 50 friends
Begin new game plus
Have 10 friends
Start a multiplayer game
Defeat the Nether King in Casual difficulty
Defeat the Nether King as an Outlander
Defeat the Nether King
Defeat the Dark Alchemist
Defeat Cacklespit
Defeat Vyrax
Obtain a tier 2 skill bonus
Defeat Killbot
Defeat Thiss
Socket 50 gems into items
Defeat 100 champions
Use an enchanter 50 times
Sell 500 items
Take 50,000 steps
Defeat Bloatfang
Defeat the Grizzled Alpha
Fish using dynamite
Defeat Boletus Rex
Squish 100 critters
Recover 10 gems from items
Defeat the Siege Guardian
Destroy a socketed gem
Teach a pet a spell
Defeat Ezrek Khan
Send your pet to town
Defeat the King In Masks
Defeat Aruk
Defeat the Artificer
Learn 4 spells
Explode 1,000 enemies
Learn a spell
Defeat the Manticore's Mate
Defeat the Manticore
Deal 1,000 critical strikes
Fish 10 times
Open 100 chests
Use an enchanter 10 times
Defeat Grand Regent Eldrayn
Find a secret room
Defeat Kidrik the Mauler
Defeat Chillhoof
Defeat 25 champions
Defeat King Pogg
Take 10,000 steps
Use 50 potions
Defeat the Winter Widow
Break 100 breakables
Recover a gem from an item
Defeat General Grell
Defeat One-Eyed Willy
Explode 100 enemies
Obtain a tier 1 skill bonus
Defeat Mordrox
Wear a completed armor set
Open 20 chests
Trade an item with another player
Socket a gem into an item
Defeat the Fallen Guardian
Join a multiplayer game
Add a friend