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