The United National Heavyweight Championship[1] (often shortened to UN Championship) was a professional wrestling title in the Japanese promotion Pro Wrestling Zero1.

It was one of Zero1's top two singles titles, along with the World Heavyweight Championship.

The title was created on January 31, 2004 as the NWA United National Heavyweight Championship.

Masato Tanaka, then known as Masa Tanaka, defeated Steve Corino in an Indian strap match to become the first champion.

There were a total of 26 recognized champions who had a combined 32 official reigns.