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