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