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