The Leviathans Add-on for Stellaris has 12 achievements.
Restore an ancient warship
Destroy a wraith
Uncover the secrets of an ancient fortress
Defeat a horrifying invader
Destroy an enclave
Hatch the egg
Support the Artisan Troupe for 10 years
Purchase a rare resource from the Traders
Birth a new universe
Take a trophy from a stellar being
Recruit a scientist from the Curators
Lead the non-aligned powers to victory against an awakened empire