Ultraman Millennium (อุลตราแมน มิลเลนเนียม Xultrāmæn Milleneīym) was one of the Ultramen created by Chaiyo Productions of Thailand, under a project named Project Ultraman, which is claimed to be due to confusion with a contract made with Tsuburaya Productions. After the end of Tsuburaya's long legal battle against Chaiyo Productions, Ultraman Millenium's show and merchandise were canceled, including two other Ultras were made by Chaiyo, named Dark Ultraman and Ultraman Elite. Ultraman Millennium's appearance is very similar, if not based on Ultraman Powered's.
Returning to Earth, Ultraman Millennium fuses with his human host (played by Mathew Dean) under Mother of Ultra's instructions. As a result from his consecutive training, he has gained a lot of new techniques, and has gotten stronger. Saving the Earth from the Dimensional Graveyard and fighting with Alien Baltan during the "Dark Ultra Crisis" has gained him considerable recognition from the Ultra Brothers, who accepted him and assigned him the duty to protect the Earth from a new disaster that will come with greater foes to deal with.
- Height: 40 m
- Weight: 40,000 t
- Age: 2,600 years old
- Human Host: Captain Shu from AET III, Mathew Dean (Actor's Name)
- Transformation Item: Warp Changer
- Eyes: Glowing blue like Ultraman Powered's, Millennium's eyes are unique among the Ultra Brothers.
- Color Timer: Millennium's Color Timer is designed oddly similar to the round table shown in the trailer.
In two live stage shows, Ultraman Millennium had two different human hosts. In Ultraman Live Show in Bangkok, the host was Captain Shu, portrayed by Thai actor Tharakorn Sooksomlert. In Ultraman Live Show 4D, the host was Shin, portrayed by a Japanese actor, Seigi Ozeki.
In Project Ultraman, Millennium's Host was played by actor Mathew Dean. His transformation device was a Beta Capsule-like object known as the Warp Changer.
- Luna Blast Ray: What is presumed to be his finisher beam.
- Orion Arrow: What is presumed to be arrow-shaped energy projectiles.
- Double Arm Shot: What is presumed to be energy shots from the arm.
- Cross Cutter: What is presumed to be an energy slicer.
- Extreme Wide Shot: What is presumed to be an extremely powerful version of the Wide Shot used by Ultraseven.
- Timer Ray (Name Unknown): A blast of energy fired from his Color Timer.
- History of Tsuburaya's legal battles against Chaiyo Productions, and the creation and cancellation of Ultraman Millenium, Ultraman Elite and Ultraman Dark.