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