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