Black List

A list of people/organizations to be shunned. http://en.wikipedia.org/wiki/Blacklist

Associated heavily (in the US) will the Hollywood Blacklist of Joseph McCarthy. http://en.wikipedia.org/wiki/McCarthyism

In computing, can be a list of machines (IP addresses) to be blocked from connecting, or list of EMail addresses to be automatically treated as spam without even checking the content (SpamWars). http://en.wikipedia.org/wiki/Blacklist_(computing)

Opposite: White List http://en.wikipedia.org/wiki/Whitelist