It can't be seen, can't be felt, can't be heard, and can't be smelt. It lies behind stars and under hills, And empty holes it fills. It comes first and follows after, Ends life, and kills laughter. What is it?

The dark

Step-by-step explanation:

I was about to say air but then I thought about it more and realized it is the DARK.

We cannot see in the dark, we cannot feel it because it is not a substance, we cannot smell it because it has no smell. It is everywhere in space, which includes behind stars, and it is dark under hills because there is no light. It ends life because at the end of our lifetimes we are laid to rest under the ground (depending on the funeral or whether or not a person get's cremated [burned to ashes[) and it kills laughter because the second we speak about a dark subject, the laughter we may be having dies.

Is that the answer?

-R3TR0 Z3R0

a=r

d=q

c=p

b=s

hope this !