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