* SugarWiki/AwesomeMusic: The series' first opening is [[https://www.youtube.com/watch?v=eKKzMkQDWbA Eiyuu]] by DOA, whose grungy, hard rock performance will clue viewers in on the [[DarkerAndEdgier general tone]] of Nexus.
** [[https://www.youtube.com/watch?v=p2DPzouBi9A Heroic]] and [[https://www.youtube.com/watch?v=iVK8IZJs86c Encounter]] also provide good examples.
** The second OP, [[https://www.youtube.com/watch?v=eaFWg0p-wyU&feature=related Aoi Kajitsu]], kicks ass as well.
* CompleteMonster: [[BigBad Dark Zagi]] ("Evil God of Destruction"), alias Unknown Hand, is an evil, heartless, genocidal tyrant from another world. Created to be a force for justice, a clone of Ultraman Noa, instead he chose to [[TurnedAgainstTheirMasters kill off his creators]], slaughtering so many of their people that they abandoned their planet and destroyed it to be rid of him. Zagi survived, and simply [[MonsterProgenitor created an army of Space Beasts]], including [[Film/UltramanTheNext Beast the One]], to take over the universe. He sent that monster to Earth, making him [[GreaterScopeVillain indirectly responsible for everything that went wrong]] in ''Film/UltramanTheNext''. In the series proper, Zagi was beaten before the events of the series and destroyed, leaving behind his energy core and his soul. To restore his power, he [[DemonicPossession possesses a random man]], killing him slowly and taking over his body. Crafting the alias of Mitsuhiko Ishibori, Zagi starts a long gambit to regain his powers, sending Space Beasts across Japan and creating two more Dark Giants to attack Nexus and kill as many people as they can. At one point, Zagi actually kills a little girl's parents right in front of her and laughs about it. Eventually, Zagi succeeds in his gambit, and reveals himself by casually shooting his loyal partner in TLT. Nagi Saijyo, the girl Zagi personally orphaned, chases him and confronts him with the power of Ultraman Nexus. Zagi, who's revealed himself as [[TheMole Ishibori]], simply mocks her, captures her, and [[ColdBloodedTorture tortures Nexus's power out of her body]] before absorbing it into himself and regaining his true form. Ascending to Tokyo, he orders all of his Space Beasts to attack the entire planet while he personally rampages through the city. Zagi was a remorseless, twisted killing machine, and responsible for much of the suffering that occurred in this series.
* FridgeBrilliance: The final battle between Ultraman Noa and Dark Zagi ended with a BeamOWar. Prior to that, try witnessing the scene itself with what the series portrayed them so far: Noa stands on Earth, where he is surrounded by mankind while Zagi was in space with nobody else around him. Up to the series' finale, Nexus continues to grow stronger by forging new bonds with humans, whereas Zagi manipulated the Space Beasts and Dark Giants to his liking and treated them as disposables. At the end, the [[HeartIsAnAwesomePower bonds Nexus had made with mankind allowed him to win]] whereas Zagi has nobody else to support and died alone in the cold vacuum of space.
** It probably helps that the more seasoned and stronger Noa is just going up against a Zagi who is pretty much out of shape.
* FridgeHorror: The kaiju are portrayed as genuinely horrifying; almost all of them feed on humans (onscreen!) and each one has its own sinister modus operandi. People die horribly, and those who survive are left broken and traumatized, many to the point of insanity. DarkerAndEdgier, right? It would be, except none of the Space Beasts are all that different from previous Ultra-kaiju. Even beloved classics like Red King and Gomora likely inflicted the same terror upon the humans they menaced.
** [[spoiler: Jun Himeya's Meta Field collapses during a fight with the Space Beast Golgolem. As it shatters, the alien looking structures in the field rupture and the area floods with strange frothy liquid. The Meta Field is later revealed to be a projection of the [[CastFromHitPoints host's own physical essence]]. What you're watching is Ultraman's internal organs burst.]]
* HarsherInHindsight: Himeya's disappearance in episode 24 becomes this when his actor Yusuke Kirishima disappeared from the entertainment world since circa 2010, making any reunion of ''Ultraman Nexus'' cast a lot harder without him. Just to twist the knife further, Himeya's last words to Komon before disappearing was "''the light is a bond''", yet Kirishima has made little effort to return to ''Nexus'' or the Ultra Series as a whole.
** ...until 2023, when Kirishima announced [[https://twitter.com/yusuke_kiri/status/1730914616820318447 on Twitter/X]] that he would be reprising his role as Himeya for a stage show!
* HilariousInHindsight: Years after ''Nexus'' aired, ''Anime/DeliciousPartyPrettyCure'' would use another kind of subspace called Delicious Field, which functions and is used in the exact same way as Nexus' Meta Field (bringing their fight to a pocket dimension so collateral damage can be avoided, along with keeping their SecretIdentity). Also, as a LighterAndSofter take on this concept, the Delicious Field's landscape and aesthetics are the [[SugarBowl exact opposite]] of Meta Field's downright EldritchLocation.
* ItWasHisSled: [[spoiler:Mitsuhiko Ishibori being Dark Zagi]] is something that any fans would highlight, as well as the fact that [[spoiler:Nexus is the devolved form of [[PhysicalGod Ultraman Noa]].]]
* MoralEventHorizon: [[spoiler: The reveal that the [[BigBad Unknown Hand]] is actually Night Raider team member Mitsuhiko Ishibori is accomplished by him casually shooting Shiori Hiraki, his always bubbly partner, at point blank.]]
* StoicWoobie: [[spoiler: Night Raider gunner Shiori Hiraki is revealed to maintain her [[GenkiGirl perpetually upbeat personality]] to hide her emotional distress from her boyfriend being mindwiped into forgetting her and marrying her best friend.]]
* TearJerker: Jun Himeya gets to watch an orphan named Sera get blown to bits in front of his eyes.
* WhatDoYouMeanItsNotForKids: [[ScrewedByTheNetwork It's Ultraman...]][[MisaimedMarketing Of course kids will love it!]] This issue was mostly avoided in the franchise until ''Series/UltraSevenX'', which became a full-blown DarkerAndEdgier ''Ultraman'' show.