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