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