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