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