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