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