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