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