Yapool, an ancient interdimensional creature tries to conquer the Planet Earth with his army of monsters called Choju. The newest member of the Ultra Brothers, Ultraman Ace, arrives on Earth to aid humanity in the battle against Yapool. Touched by the sacrifices of Seiji Hokuto and Yuko Minami, he revives them and grants them the Ultra Rings, which allows them to transform into Ultraman Ace in times of need.
At this time, the Ultra Series was facing direct competition from series such as Kamen Rider. This caused Ace to start shifting from a sci-fi/mystery adventure to full-tilt superhero fantasy fare. Also, all previous Ultraman like Ultraman, Ultraseven, Ultraman Jack (from Return of Ultraman) and also with Zoffy make more frequent appearances here, whereas they only made guest appearances in the previous show Return of Ultraman. In addition to this, the writing became darker, slightly less episodic, and far more intense, as Ace struggles against the forces of Yapool, the first big bad of the entire franchise. Civilian deaths are more frequent, and monsters are often killed in extremely gory ways, although there is not as much death as would come two years later, with the advent of Ultraman Leo.
Ace is also notable because it introduces the first female host to the franchise, Yuko Minami. Unfortunately, gender prejudice of the time caused backlash against Yuko, forcing the producers to have her written out of the show. It also introduced the concept of recurring antagonists, with Yapool being the major villain.
- Seiji Hokuto
- Yuko Minami
- Noriko Mikawa
- Goro Ryu
- Ichiro Yamanaka
- Tsutomu Konno
- Kozo Yoshimura
- Kaji Yoichi
- Giron Man
- Alien Metron Jr.
- Muruchi II
- Alien Antira
- Ace Killer
- Ace Robot
- King Crab
- Black Pigeon
- Android Couple
- King Kappa
- Space Mask
- Black Satan
- Giant Yapool
- Mazaron Man
- Alien Orion
- Alien Hipporito
- Red Jack
- Bad Baalon
- Alien Fire
- Alien Steal
- Woo II
- Verokron II
- Alien Revole
- Alien Simon
- Jumbo King
- Seiji Hokuto (北斗星司 Hokuto Seiji): Keiji Takamine (高峰 圭二 Takami)
- Yuko Minami (南夕子 Minami Yūko): Mitsuko Hoshi (星光子 Hoshi Mitsuko) (1-29, 39 & 52)
- Noriko Mikawa (美川 のり子 Mikawa Noriko): Keiko Nishi (西恵子 Nishi Keiko)
- Goro Ryu (竜五 郎 Ryu Goro): Tetsurō Sagawa (瑳川哲朗 Sagawa Tetsurō)
- Ichiro Yamanaka (山中一郎 Yamanaka Ichiro): Okita Shunichi (沖田駿一 Shunichi Okita)
- Tsutomu Konno (今野勉 Konno Tsutomu): Masaaki Yamamoto (山本正明 Yamamoto Masaaki)
- Kozo Yoshimura (吉村公三 Yoshimura Kozo): Koyo Sano (佐野光洋 Sano Koyo)
- Kaji Yoichi (梶洋一 Yoichi Kaji): Katsumi Nakaiyama (中山 勝己 Nakaiyama Katsumi) (1-3, 5-14, 27, & 31)
- Dan Umezu (梅酢ダン Umezu Dan): Umezu Akinori (梅酢秋則 Akinori Umezu)
- Kayoko Umezu (梅津香代子 Umezu Kayoko): Rie Miyako (宮野リエ Miyako Rie) (29-43)
- Narrator (ナレーター Nareta): Shin Kishida (岸田森 Kishida Shin)
- Ultraman Ace (ウルトラマンエース Urutoraman Ēsu): Voiced by Goro Naya (納谷悟朗 Naya Gorō)
- Ultraman (ウルトラマン Urutoraman): Voiced by Mahito Tsujimura
- Zoffy (ゾフィー Zofī): Voiced by Osamu Saka (episodes 5 & 35), Goro Naya (episode 5 grunt), Masao Nakasone (episodes 5, 13 and 26 grunt), Osamu Ichikawa (episode 13), Keisuke Yamashita (episode 23)
- Ultraseven (ウルトラセブン Urutorasebun): Voiced by Osamu Saka
- Ultraman Jack (ウルトラマンジャック Urutoraman Jakku): Voiced by Keisuke Yamashita (episode 13)
- Father of Ultra (ウルトラの父 Urutora no Chichi): Voiced by Masao Nakasone (low-pitch grunts), Tetsuya Kaji (speaking voice)
- Yapool (ヤープル Yapurū): Hirofumi Takada (高田裕史 Takada Hirofumi)
- Ultraman Ace (ウルトラマンエース Urutoraman Ēsu): Tadashi Nakanishi (中西正 Nakanishi Tadashi) (1-2) & Shoji Takeuchi (武内正治 Takeuchi Shoji)
- Choju (超獣 Chōjū): Toru Kawai (河合 徹 Kawai Tōru) (1-12, 25-39, 41-47), Isao Zushi (図師勲 Zushi Isao) (13-24), Tokio Yamaji (矢島登喜男 Yamaji Tokio) (48-52), Kin'ichi Kusumi (久須美 欽一 Kusumi Kin'ichi) (41-42)
- Ultraman Ace (ウルトラマンエース Urutoraman Ēsu)
A Malaysian DVD was released in 2014. It contains a Cantonese/Chinese dub, English subtitles, Chinese subtitles and Malay subtitles.
Mill Creek is also set to release the complete series on May 12, 2020, under the Steelbook and Blu-Ray releases.
- Ace was originally going to be titled Ultra A, but was renamed when Tsuburaya discovered that title was already copyrighted. The fact that Ultra A was renamed Ultraman Ace is important, because it established that Ultraman would be the title of all the heroes to come after, as opposed to just Ultra.
- Up till this point, Ultra had been the title, not Ultraman, as indicated by the name of Ultraseven. (Ultraman Jack had originally intended to be an updated design of the original Ultraman, and had not been given his name yet)
- This would have meant that Ultraman would be the only Ultra with the title of Ultraman, and all the others would be known as Ultra -- like Ultraseven. It is unknown what this would have meant for Ultraman Jack.
- This is the first series to introduce a being of light that is not part of the Ultra Brothers, that of course being Father of Ultra, the Supreme Commander of the Space Garrison.
- This the first Ultra Series which contains a preview of the next episode at the end of the episode.