A god-king is a wiki leader to whom all bureaucrats and sysops are accountable. A god-king can create policy unilaterally and has the final say on all disputes that arise. Often, the god-king is the owner of a wiki. In the case of Wikimedia, it was initially Jimbo Wales, who founded the organization, and whose associates made up a majority of the governing board in Wikimedia's early days.
Some wikis, such as RationalWiki, have no single god-king, but rather are ruled by an elected committee of moderators. While a god-king has the authority to do whatever he wants on, to, or with the wiki for any reason or no reason, such a committee usually is only allowed to discipline users for cause, and it can only overturn community decisions in sysop and bureaucrat elections for cause.