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