Egypt, 11th century. When a famine ravages the country, the prosperous Andalusian kingdom of Denia comes to the aid of the sultan, who, in gratitude, gives Denia the most sought-after and coveted object in all of Christendom.
Unfortunately the movie Onyx: Kings of the Grail is not yet available on HBO Max.
| Directing | Roberto Girault | Director |
| Crew | Valentín Diez Morodo | Thanks |
| Production | Óscar Cifuentes | Producer |
| Production | Óscar Cifuentes | Executive Producer |
| Production | Pedro Palacios | Executive Producer |
| Writing | Roberto Girault | Writer |
| Writing | Luis Reneo | Writer |
| Writing | Margarita Torres | Writer |
| Camera | Rafael Bolaños | Director of Photography |
| Sound | Eduardo Ortega | Original Music Composer |
| Production | José Jaime Linares | Production Director |
| Art | Itziar Sagasti | Production Design |
| Editing | Adoración G. Elipe | Editor |
| Costume & Make-Up | Giovanna Ribes | Costume Designer |
| Sound | Carlos Lidón | Sound Recordist |
| Sound | José Luis Alcaine Bartolomé | Sound Designer |
| Directing | Patricia Ordás | First Assistant Director |
| Directing | Chris Downs | Second Assistant Director |
| Directing | Daniel M. Caneiro | Script Supervisor |
| Production | Carla Hool | Casting Director |
| Crew | Mabel Villagra | Technical Advisor |
| Production | Eduardo Lis | Production Manager |
| Lighting | Raúl Pavón | Gaffer |
| Camera | Jorge Casabán | Key Grip |
| Crew | Miguel Olarieta | Special Effects |
| Costume & Make-Up | Alicia López | Hair Department Head |
| Costume & Make-Up | Sonia de la Fuente | Makeup Department Head |
| Camera | Marco Mastropietro | Still Photographer |
| Directing | Luis Reneo | Second Unit Director |
| Visual Effects | Helmuth Barnert | Visual Effects Supervisor |
| Sound | Miguel Ángel Caprara | Foley Artist |
| Writing | Margarita Torres | Book |
| Writing | José Miguel Ortega | Book |
