"To be honest, this wasn't what I expected at all. In this darkness, when you're disadvantaged, it's fitting that you're eliminated here!"
- ―Dark Faust, episode 8
Dark Faust (ダークファウスト Dāku Fausuto) was the first of the evil Ultramen created by Dark Zagi to battle Ultraman Nexus. Years ago Nosferu, Dark Mephisto's pet, killed the Saida family including Riko Saida. Mephisto had his loyal agent Dark Faust possess Riko to hide from Ultraman Nexus.
Despite the masculine voice, and appearance, Faust is confirmed to be a female Ultra in the magazines.  Furthermore, she was never called by full name, only referred to as Faust (ファウスト Fausuto) by Himeya and the Night Raiders, including herself.
- Giant of Darkness (闇の巨人 Yami no Kyojin)
- Red Giant of Death (赤き死の巨人 Akaki shi no Kyojin)
A year before the events of Ultraman Nexus, Riko Saida met Kazuki Komon at a zoo and the two hit it off immediately. That night Riko drove home with her mother, father and brother, only to be attacked by the Space Beast Nosferu. The beast disabled their car and though her family was killed when the car exploded from the monster's attack, suddenly a Night Raider, Shinya Mizorogi, appeared and aimed his weapons at the Space Beast. He then turned his weapon on the unsuspecting girl and fired straight into her face. After that she was revived by Mephisto's dark power as a human puppet. Instead, she was a suitable vessel for his servant, the lesser Dark Giant known as Faust. Since then, Riko and Komon started a relationship. All the while, Riko lived in an imagined world that was forced upon her, where her family was still alive and well.
In the present day, the light of Noa found its second vessel, Jun Himeya. As Jun was about to turn into Nexus because of Bugbuzun's reappearance, Faust appeared and started to use dark energy bolts to attack him. Faust claimed she was Jun's shadow, and Jun soon turned into Ultraman Nexus. After going into Junis Form, Nexus created his meta field. Faust overpowered it with her own dark field. In this land of darkness, the two clashed and seemed to be evenly matched until Faust used the Dark Cluster, causing a volley of dark energy balls to rain down on Nexus. Just as the hero got up, his color timer began to blink and Faust began to overpower him. However, Nexus didn't give up and after using the Cross Impulse attack, Faust retreated within the Dark Field, vowing to return.
True to her word, Faust returned as Jun was investigating Lafleya's latest three victims. Wanting the human to turn into Nexus, Faust provoked him until the former complies. The two giants soon fought, but once Night Raiders appeared, Faust vanished. As Nexus fought Lafleya in the Meta Field, Faust appeared from underground and used the dark field once again. The combined effort of Lafleya and Faust seemed to be too much, but after some clever usage of the Phase Feather attack, Faust soon retreated as did Lafleya. However, one of the Phase Feathers deflected by Faust hit the Night Raiders' Chester, knocking it out of the sky.
That morning Komon woke up in the Chester with Nagi missing from her seat. As he went to investigate, he found his girlfriend, Riko, unconscious and holding Nagi's dog tag. Upon Nagi's appearance she tried interrogating Riko, even throwing Komon out of the way, but the frightened woman had no answers for her. That night Lafleya and Nexus fought once again with Faust returning, but after the Night Raiders used the Strike Vanisher to destroy the Space Beast, Faust was heavily damaged and was forced to retreat. Around this time Riko started having visions and hearing voices. She was being tormented by Faust and her master Mizorogi, who erased her memories to turn her into a true puppet.
Faust showed up once again after Riko went missing. Komon encountered the fiend, blocking her path on the road. Dodging his questions about Riko, she was about to kill Komon, but Jun showed up just in time and fought the fiend as Nexus. The two fought once again, but this time Faust didn't use the dark field and was soon defeated. After retreating, Faust was preparing to fight her final battle with Nexus. Komon and Jun found Riko in the forest, but now Faust was in control and revealed the devastating truth about Riko to Komon before transforming. The two giants met once again and clashed in Faust's dark field, with Komon somehow sucked inside with them. By standing over Komon, Faust used him as a hostage to pummel Nexus. With the hero down, Faust latched on to him, to ready to drain him of his Light energy.
- ―Dark Faust as Riko
As Faust began to drain Nexus' energy, Komon fired a shot at Faust, causing her to stare at him. Unknowingly to him, his shots revived the sealed memories of Riko to the astonishment of Faust's watching master. Because Riko now possessed Faust, the dark giant's host was dead. She released Nexus weakly, while she continuously stared at him. Mephisto summoned Nosferu to kill Komon, but Riko sacrificed Faust's body, which was now her own, giving her life for her beloved. After Nexus blew Nosferu to pieces with the Cross-Ray Schtrom attack, Komon moved to Riko's side, and stayed with her until she died. In his arms, she disappeared into particles of light, leaving behind a devastated Komon to battle with serious depression. Even though Faust was now dead, there would be worse agents of darkness to attack the Earth, such as her master, who would now directly target Komon.
- Eyes: Faust's eyes can see perfectly in the dark of night or her own Dark Field.
- Energy Core: Faust's resembles a normal Color Timer, but it functions like Nexus', it is also black but flashes red when she is weak and/or injured.
- Protector: The gold stubs next to her Energy Core, they are the sturdiest part of her anatomy and almost indestructible.
- Ultra Armor: Faust's Ultra Armor is typical but it had black markings and is also mismatched and asymmetrical.
- Weakness: Despite her immense power, Faust is apparently the most feeble among other Dark Giants, seeing how she always retreated upon being hit by an unexpected counterattack.
Unlike most Ultras, Faust was only seen transforming once. Her transformation had more in common with Ultraman the Next than Nexus or Mephisto. Faust didn't use a transformation device and instead Riko's body was covered in a dark blue light and transformed, by morphing the image of Riko into Faust.
- Dark Cluster (ダーククラスター Dāku Kurasutā): Faust can create a large dark energy ball with her hands, it turns into dozens of dark energy balls, raining down on her enemies.
- Dark Feather (ダークフェザー Dāku Fezā): Faust can emit a powerful, dark energy blast from her left hand by first placing it over her right hand, and then thrusting it forward.
- Dark Ray Jabirom (ダークレイ・ジャビローム Dākurei Jabirōmu): Energy attack emitted from the outstretched hands, rivals the power of the Over-Ray Schtrom. Despite having the word "Ray" in its name, it is more of an energy blast than a stream of darkness.
- Size Change: Faust can change her size between human size and giant at will. She does this in a column of dark energy.
- Meta Field Invasion: Faust can invade Nexus' Meta Field.
- Dark Field Deployment (ダークフィールド展開 Dāku Fīrudo Tenkai): Faust can create a meta-field of a negative phase, strengthening Dark beings like her but weakening beings of Light like Ultraman, this is especially so when it over powers Nexus' Meta Field. Faust has only ever generated it to counter Nexus' Meta-Field implying she can only alter the Phase and not generate it.
- Energy Absorption: Faust can absorb the energy of her foes when she is in physical contact with them. However, she rarely uses this ability as the foe has to be weakened already.
- Dark Flasher (ダークフラッシャー Dāku Furasshā): Faust can create green blasts from her palms, but these only cause small explosions.
- Dark Shield (ダークシールド Dāku Shīrudo): Faust can create a barrier with one hand or both. It resembles a purple pool of water.
- Teleportation: Faust can become invisible and teleport elsewhere, usually only doing so to escape.
- Dark Slider (ダークスライダー Dāku Suraidā Unused)
- Dark Lifter (ダークリフター Dāku Rifutā Unused)
- Faust Kick (ファウストキック Fausuto Kikku Unused)
Ultra Hero Series
- Dark Faust (2005)
- Release Date: November 11
- ID Number: N3
- Price: 700 yen
- JAN/ISBN: 4543112254757
- Materials: PVCReleased as part of the Ultra Hero Series N lineup, Dark Faust is a 6-inch soft vinyl figure with 3 points of articulation, and is entirely molded in red and sports black and silver paint operations. As with most Ultra Hero Series releases, Dark Faust comes with a collectible foldable data card. Continuing the tradition of sharp-booted figures, Dark Faust features a copyright sculpted on her back.
- Her voice actor, Tetsu Inada nominated Faust as one of his favorite characters in the tokusatsu series, as he simultaneously did the voice of Doggie Kruger/DekaMaster from Tokusou Sentai Dekaranger in the same year (2004).
- This is rather an irony, as Tetsu previously voiced the grunt of Ultraman Cosmos from his latter two movies, with said character's starring show is portrayed as a direct opposite to Ultraman Nexus.
- Faust's possession of Riko is a dark and sinister version of a classic staple of the Ultra Series which stretches back to the original Ultraman. It is where an Ultra merges with a recently killed human making them their host and reviving the deceased person.
- It has been argued by some that Faust died not when Nosferu stabbed her in the back but when Riko took control of her body to save Komon. This is due to the fact that Mizorogi was able to call upon the power of Mephisto again without being control by the darkness, implying the personality of Mephisto was gone.
- She is also commonly mistaken by fans to be a male Ultra due to lacking feminine traits. This was purposely done by the designers. The most likely reason for this is being to hide any hints or foreshadowing her host being Riko. In the video game, Faust is given a more obviously feminine body.
- Faust's design motif is that of a clown/harlequin.
- The harlequin is an ancient type of clown that is said to have inspired the Hellequin, a demonic black face, clown servant of the devil in certain plays, which makes sense giving Faust's dark nature, and her being the minion of Dark Zagi.
- The shape of Faust's color timer, is similar to Ultraman Zearth's but inverted.
- She is so far the second female Ultra in the Heisei era and is the fifth in overall of the Ultra Series franchise. Alongside Camearra, she is also a dark Ultra but is nonetheless the only one to have bonded with a human host instead of creating one.
- Faust and Mephisto's names come from a German tale, often called Faust. In it the titular character makes a pack with the devil Mephistopheles, it from this tale we get the term, 'Faustian Bargain'.