Voiced By: Jeff Szusterman
Master Xandred and his Nighlok Army were sealed away in the Netherworld by the Samurai Rangers prior to the current team. He eventually wakes up and spends most of the series waiting for a way to travel to the humans dimension without drying up. He does so eventually after draining Dayu of her humanity and floods the Earth with the waters of the Sanzu River. He is stopped however by Jayden in Shogun Mode but grows and is destroyed for good by the Samurai Megazord.
Voiced By: Jeff Szusterman
Octoroo’s main goal throughout the series was to ensure that Master Xandred would be able to travel to our dimension and to flood the Earth with Sanzu River water. After Master Xandred succeeds in this, he travels on the Junk alongside Xandred as the waters of the Sanzu River floods the Earth. After Master Xandred is destroyed, the Junk sinks back into the Netherworld with him on it.
Voiced By: Kate Elliot
Played By: Rugen Du Bray
Dayu was once a human known as Dahlia who transformed into a Nighlok after her husband Deker was transformed into a Human/Nighlok hybrid. She was eventually recruited by Xandred to play her harmonium for him after learning that was the one thing that tamed his anger. She leaves the Netherworld after Xandred destroys her harmonium and teams up with Serrator after he offers to fix it. He does not keep his promise however and she turns on him. However. Xandred does fix it and she returns to work for him for a short time. She meets her demise after Xandred sacrifices her to ensure that a new seal would not work on him.
Played By: Rick Medina
Deker was once a human who was transformed into a Human/Nighlok hybrid after his house went on fire. From then on, he was cursed with a desire to duel someone and eventually chooses Jayden as that person. He is defeated midway through the series but is resurrected due to his sword Uramasa breaking in the duel. He teams up with Serrator to get his sword fixed and turns on him after it is fixed. He challenges Jayden to a duel a second time and is destroyed by him for good.
Voiced By: Derek Judge
Serrator is revived during Master Xandred’s power surge and offers his services to Master Xandred. However, Serrator is shown to have his own agenda and recruits Dayu and Deker to aide him in his plans to split the Earth in two with promises of fixing their prized possessions. He succeeds by attacking certain areas to enact a tear in the Earth. He only need Deker to attack the final wedge to enact his plan but is betrayed by him and is destroyed. He grows but is destroyed by the Samurai Shark Gigazord.
The Moogers serve as footsoldiers to the Nighlok.
The Furry Warts live on the roof the Junk and often come down to repeat words spoken by the Nighlok.
The Spitfangs serve as secondary footsoldiers to the Nighlok.
These robotic doll-like creatures are created by Serrator from paper to battle the Samurai Rangers in their Megazords.
Venjix Computer Network
Voiced By: Cameron Rhodes
Professor Cog comes from the same dimension the RPM Rangers are from and travel to the Samurai Rangers dimension to team up with the Nighlok to use their Sanzu River water to pollute the RPM Dimension. He successfully takes out five of the Samurai Rangers by teleporting them to his dimension and leads a combined army to get rid of the surviving rangers. When the Samurai Rangers returns to their dimension, he is destroyed by the combined efforts of the Red Samurai and RPM Rangers.
The Grinders serve as footsoldiers to Professor Cog during Professor Cog’s trip to the Samurai Rangers dimension.