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