So, far I have been trying to find a GM that has a brilliant record on the blackside. I'm not talking about someone like Kasparov or Fischer who dominated both sides; I want to know who has a ridiculously inequitable amount of victories as the defender, so many that this person's opponents dread the idea of being on the attack. This doesn't mean that this person has to lose a lot on white, just that he is best (of the best) on black. So far, the only player I've found with a record similar to that description is Roman Dzindshishkashvili, but there has to be a larger fish out there. Any input would be beneficial.

i don't know about records. but i would look at some of the players whose names are more associated with defences. (please no spelling corrections.)

Alekhine, Marshall, Najdorf, nimzowitsch.

although, Steinetz was known for aggressive play with white.  he was also known to always accept the gambit as black.  i wonder how that worked out for him.

Sahlo Flohr the drawing master and Peter Leko, Tigran Petrosian

I would think Rubinstein would have to be up there.

Yup! I agree.Definitely

 Thanks for contributing! This post isn't just for me. Remember that readers will not learn as much if the next 5 people agree about Rubinstein, however affirmation of another person's post is helpful. To contribute, I found something to contribute, too, in order to keep this forum alive. It is definitely obscure, but Anna-Maria Botsari is a very recent player that does well on black. Especially with the quixotic St. George Defense (1. e4 ... a6 ).

Thread misnamed. I expected it to be about Chess Records.

I would have to say Tigran Petrosian.  he may also have a ridiculously high number of draws as black, but all his games in books i see are perfect examples of how to equalize and win as black.