Ring 0

Ring 0 or zero ring or variation, may refer to:

Arts and entertainment

 * Ring 0: Birthday, a Japanese horror prequel film
 * The Ring Volume 0: Birthday, a subsequent manga

Technology

 * Ring 0 (computer security), the highest privilege level
 * Telephone dialling instructions to access a switchboard operator

Other uses

 * Zero ring, the trivial ring in mathematics ring theory
 * O̊, the letter "O" with a ring diacritical mark