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