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