Was Dolores Umbridge a Death Eater?

Answer 1

No, Umbridge was not a Death Eater. That didn't mean she was a good person. She was very self serving and only out for more power and recognition. She was not a Death Eater, but she rode their coat tails and took advantage of the situation they created to place herself in a position more to her liking. She didn't care who she hurt or took advantage of as long as she could exert her authority over others.

Answer 2

This information is never revealed in the books, and, as far as I know, J.K. has never mentioned it in any of her interviews.

But since at the ministry in book seven, in front of her offiice, ministry members were printing books on the dangers of muggle borns, it wasnt said she was angry, so theres your proof.