Here is the full list of all 18 Hollowed achievements.
Saving Inna
A life after death
Choosing Oco
Ringing the Bells
Surviving the Collapse
Meeting the god
Roaming the gods realm
Sinking deep
Running from the past
Scaling the world
Making a trade
Seeing the future
Avoiding the seeking hands
Expressing aggression
Rejecting Life
Learning the motivation
Creating a relationship
Moving forward decisively