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