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