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