The "anonymous" downvoters are there.
Perhaps you already met some of them?
If you get a downvote it can be for any reason except the one the downvoting is meant for (something most of us already expected). Fact is it is hard to judge objective for most of us.
The idea about downvoting is to fight plagiarism and to stimulate writing good content. It is also the fight against bidbots.
I am not going to tell what good content is. I already did, so did others and the steemit team did too (20 steem or more is good, less is bad but good for Steemit inc.).
Today again someone asked for help.
Help against being downvoted. I would like to give a hand but I do not know how.
Fact is I do not know how everything works here, I am not part of the Steemit team and not a big fish either. I am that dying person killing time here and elsewhere and trying to help you grow. If you write good content you can have my vote.
Steemit inc. will not help you, not even answer your comment. I suggest to ask one of the witnesses like 
In some downvote cases, you can ask the downvoter how or what via his/her discord group.
I did not check out how or what exactly happened (my connection is too slow) but if you go that far something really bad is going on. I hope by now the problem is solved.
Some downvote to get attention.
Another brave downvoter is 
.
This drama queen account welcomes us with the not very original words
Anonymous Steemit Victims Defence League: We are Anonymous. We are Legion. We do not forgive. We do not forget. Expect us.
This legion has so far not written one single example of good content.
This means you will never learn how to improve yourself. Since they also do not leave a comment and the text on the account speaks for itself you know what kind of person "we" is and the downvote is done out of revenge and "we" loves to threaten people.
The legion who hates downvoting is downvoting itself.
If you want to use your right to downvote pay 
How to defend yourself?
You can fight back and downvote every post of the downvoter or... every post the downvoter resteems. If your downvote is stronger as the opponent you can have a lot of " fun" here.
You can also ignore it and write on.
Yes, you are on someone's blacklist or even on more lists but these Steemians are not the only one around here. If you built some reputation, your followers know you and your content is original (not stolen), theywill not give up on you and you have their vote.
Who downvotes you?
fill out your name or someone elses
Who did you downvote/flag?
fill out your name or someone else's
Keep in mind that everyone knows many downvotes are given for a personal reason.
The theme of a post might not be interesting for you, someone's opinion might differs from yours, but this does not make content bad!
Try to downvote for a good reason please, not out of revenge and give some helpful advice if you can, tips to improve. Most people never learned how to write a good article but that doesn't mean they can not learn it. I improved (my English too here) and with me I saw others grow.
No, if you are downvoted it is not the worse day of your life. It might look like as if the sun does not shine for you but keep in mind there is a moon, their are stars and their is always a light even if it isn't bright.
Some downvotes are worth 0. They do not effect your earnings and if remember upvotes are their to fight the downvotes.