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