A KoS ("Kill on Sight") was formerly the worst punishment on GameFAQs. It happened when a user violated the TOU to the point where the administrators felt the user should no longer post on the site. In this scenario, the user either went under "Name KoS" (allowed on the site, but banned upon revealing identity) or "Full KoS" (the user's IP address(es) may have been blocked from creating accounts and moderators told to suspend the user's accounts whenever they are found). Very few users ever reached KoS status.
It is speculated that the system disallowed users who have an ISP with a high number of banned accounts from making accounts on anything except pending review. This usually provided a small amount of protection aagainst KoSed users trying to get back in. CJayC was known to go as far as banning/reviewing names of notorious users from account creations and banning/reviewing commonly used passwords of notorious users.
In extreme cases, the user's ISP and othe authorities may be contacted. CJayC got a few websites shutdown for hosting private information from GameFAQs, and he issued a cease-and-desist order on more than one occasion.