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