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