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