Since no one answered you, that black ooze shaped like a man is called Armus. He is the alien who kills the original security officer Tasha Yar in the first season.

Hey, that’s fine. It’s a wide spanning series with a lot of ins and outs and what have you. Don’t be discouraged for asking.

edit: Thanks for clarifying, teft.

I’ll give you a hint. Its big black and liquidity