I am a horse that will not run, And in the dark I won't be fun,............... What am i ?

Question

I am a horse that will not run,
And in the dark I won't be fun,
I cause a stir, perhaps a scream,
To have me you will not be keen,
You'd like to keep me on a tether,
But you wont escape my appearance forever.
What am i ?

Answer 1

Nightmare .
Because Mare - female version of horse.
And nightmare is never a fun in the night