Here is the full list of all 45 LEGO Marvel Super Heroes achievements. It takes around 30-35 hours to unlock all of the achievements on Windows.
Complete game 100% (Single Player)
Perform all big LEGO figure transformations
Turn into Stan Hulk
Rescue Stan Lee from every peril (Single Player)
Unlock all True Believers (Single Player)
Perform Hulk's special move on Loki
Create a character called “Trevor” in the character customizer
Collect 1,000,000,000 studs (Single Player)
Perform a special throwing move as Colossus on Wolverine
Collect Doc Ock, Sandman, Mysterio, Kraven the Hunter, Electro and Vulture (Single Player)
Collect all traditionally heroic mutants (Single Player)
Team up Captain America with Human Torch (Co-op)
Unlock all animal-themed characters (Single Player)
Collect all traditionally evil mutants (Single Player)
Unlock all the Guardians of the Galaxy (Single Player)
Collect all Avengers characters in the game (Single Player)
Read a comic in Deadpool's room on the Helicarrier
Play as Agent Coulson
Drive to the Baxter Building as Magneto in the Magneto Mobile
Collect Howard the Duck (Single Player)
Collect all Iron Man armors (Single Player)
Complete House Party Protocol
Create a custom character
Complete Level 15 - The Good, the Bad and the Hungry
Complete Level 14 - A Doom with a View
Complete Level 13 - Magnetic Personality
Complete Level 12 - Rapturous Rise
Destroy 100 vehicles in the Manhattan hub
Complete Level 11 - Taking Liberties
Transform into the Hulk 50 times
Complete Level 10 - That Sinking Feeling
Complete Level 9 - Doctor in the House
Defeat 100 enemies as the Thing
Complete Level 8 - Juggernauts and Crosses
Unlock Black Cat (Single Player)
Complete Level 7 - Bifrosty Reception
Complete Level 6 - Red Head Detention
Regenerate as Wolverine
Complete Level 5 - Rebooted, Resuited
First time turning Mister Fantastic into a teapot
Complete Level 4 - Rock up at the Lock up
Complete Level 3 - Exploratory Laboratory
Complete Level 2 - Times Square Off
Complete first Helicarrier skydive
Complete Level 1 - Sand Central Station