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