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