Pope Fabian
Others are obscure because of the "damnatio memoriae" surrounding the lives of antipopes, or because they were refused burial due to excommunication. Some of those can be presumed to have been buried unceremoniously in the monasteries to which the antipopes were confined after submitting or losing power. The exception is Hippolytus of Rome, the first antipope, who was translated to Rome by his former rival Pope Fabian following his martyrdom, and is regarded as a saint.