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