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