My prefix is a big loud noise
My suffix are small animals
Somewhere in my middle is a synonym of beneath
Kids are my fans
I think the answer is:
Thundercats, thanks to @PaigeMeinke
Thunderbirds
My prefix is a big loud noise
Thunder
My suffix are small animals
Cats, fits better with "small animal"..
Birds, although they can also be pretty big..
Somewhere in my middle is a synonym of beneath
Under
Kids are my fans
They are..