The Giants of Darkness in Ultra N Project is a group of Dark Ultras led by their creator, Dark Zagi in their fight against Ultraman Noa and his devolved form, Ultraman Nexus. Despite being recognized as a group, the team members operated independently under their master's orders, with one replacing the other should the assigned Dark Giant was killed in action.
In Kanji, the group's name is either written as Yami no Kyojin (闇の巨人) or Ankoku Kyojin (暗黒巨人 ).
"I predicted that Nagi would receive Ultraman's light. Creating Faust and Mephisto and having you (Ultraman) fight them was to strengthen the power of the light. I used Riko Saida and Mizorogi to plant the darkness in your heart, Nagi. I was in Night Raider because it was convenient for me. It was all a tool for me to return back to my original form."
- ―Mitsuhiko Ishibori/Dark Zagi
After losing his physical form to Ultraman Noa and had to forge the identity of Mitsuhiko Ishibori, Dark Zagi begins to construct a long term plan centering on Nagi Saijyo. Having predicted that the light of Noa would choose her, created the Giants of Darkness as a means of furthering this plan, first by having Dark Mephisto to sway Shinya Mizorogi to their side and orchestrating the death of Riko Saida for Dark Faust to use her as a vessel.
The Giants of Darkness started their actions in the present day when the Night Raider had recruited Kazuki Komon as their newest member. As Mizorogi observed from the shadows, Dark Faust fought against Himeya on multiple occasions and even targeting Komon by guilt-tripping the young man for his part in Riko's death. Mizorogi would later dispose Faust through Nosferu when the real Riko Saida started to suppress her dark giant, exposing himself as Dark Mephisto to the Night Raiders in the process. Mizorogi/Mephisto was seemingly killed in the fight. With Mizorogi survived and was rendered amnesiac, hence Zagi was forced to take an active involvement in subsequent Space Beast attacks, such as hacking into the TLT database to erase their data on Nexus' beam attack and empowering Space Beasts through Dark Field G.
When Mizorogi was arrested by TLT, Zagi brainwashed Hiroyuki Misawa into Mephisto's clone to take over his predecessor's duties and silencing him from exposing Zagi's secrets. Mizorogi regained the ability to transform into Mephisto and sacrificed himself to restrain his doppelganger for Nexus to finish both of them. In his final breath, Mizorogi reported to Nagi of Zagi being among the TLT's ranks. Following the destruction of Izmael, Nexus' light was passed on to Nagi, just as Zagi predicted. After slaughtering his way through the Night Raiders, Ishibori admitted his true identity and his motives to strengthen Nexus through his Giants of Darkness as stepping stones while feeding Nagi hatred. Nagi's transformation into Nexus triggered a trap by Lethe to absorb Nagi's hatred and Nexus' light, converting them into dark energies for Dark Zagi to be resurrected and finally beginning his reign of terror. Zagi was defeated when the light of Nexus was passed on to Komon, who restored Nexus to his true form, Noa.
Ultraman Nexus TV COMPLETE DVD-BOX: Second Coming - Dreams -
Three years after Zagi's death, Dark Lucifer appeared as his final Dark Giant that Ultraman Noa faced against.
The alternate version of Dark Zagi transformed foreign scientists Soso and Utsuutsu into Dark Mephisto and Dark Faust respectively when they sold their soul to the dark warrior in exchange for greater power. The three fought against Akiko Fuji as Giant Soldier F, wherein Zagi's beam becomes the catalyst to mutate her into Ultraman F. Fuji used her newfound abilities to kill Faust and Zagi. With Mephisto's body disintegrated by M87 Beam, Soso contemplated to destroy Earth after Utsuutsu was killed, but was prevented from doing so by Utsutsu's spirit.
- In contrast to a similarly-named team, Zagi's Giants of Darkness not only operate on independently, but were also seen as disposables for his own plans to come into fruition. In addition, each of the team members share the coloration of black and red.