Miranda Richardson.
Two different, ill-fated queens:
1. Queen Mab, in "Merlin."
In the movie she plays an evil queen that is killed.
2. Queen Elspeth in "Snow White: Fairest of Them All."
In this movie she also plays an evil queen that is killed.
The doomed mother of a doomed reporter:
Ingrid Fleming, in "Damage."
In this movie, her son, a reporter, dies by accidently falling over a railing after seeing his father having an affair with his fiancee. His mother, Miranda Richardson, is devastated by the news of her son's death and the affair. She even questions if her husband ever loved her AND suggests he should have killed himself.
Hint #1: Twisted sister:
"Sleepy Hollow"
I did look at your spoiler hints and do not think this is the exact one; however, I believe she does fit the bill. AND I freely admit, it was only my love for Blackadder that got me thinking of a goofy queen which lead to two different doomed ones. Also, Miranda Richardson is awesome.