Ultraman Dies at Sunset (ウルトラマン夕陽に死す Urutoraman Yūhi ni Shisu) is the 37th episode of Return of Ultraman. This episode is the first Christmas episode, and it also features the deaths of Ken Sakata and Aki Sakata.
To conquer the Earth, an alien from Planet Nackle studies Ultraman's abilities, and tries to find a weakness of him all to defeat him for good.
Disguising himself as a staff of the Space Radio Wave Laboratory, Alien Nackle wanted to get Ultraman out of his way of Earth's invasion. First, he revived monsters Seagorath and Bemstar to analyze Ultraman's specs and powers, then he robbed MAT's newly invented gunpowder Saturn Z. Last of all, in order to disrupt Go's mind, he started a very dirty plan...
- Hideki Go (郷 秀樹 Gō Hideki): Jiro Dan (団 時朗 Dan Jirō)
- Ryu Ibuki (伊吹 竜 Ibuki Ryu): Negami Atsushi (根上 淳 Negami Atsushi)
- Takeshi Minami (南 猛 Minami Takeshi): Shunsuke Ikeda (池田 駿介 Ikeda Shunsuke)
- Ippei Ueno (上野 一平 Uneo Ippei): Hatashi Mitsushi (三井 恒 Mitsushi Hatashi)
- Yuriko Oka (丘 ユリ子 Oka Yuriko): Mika Katsuragi (桂木美加 Katauragi Mika)
- Fumio Kishida (岸田文夫 Kishida Fumo): Ken Nishida (西田健 Nishida Ken)
- Aki Sakata (坂田アキ Sakata Aki): Rumi Sakakibara (榊原るみ Sakakibara Rumi)
- Ken Sakata (坂田健 Ken Sakata): Shin Kishida (岸田森 Kishida Shin)
- Jiro Sakata (坂田 次郎 Sakata Jirō): Kawaguchi Hideki (川口英樹 Hideki Kawaguchi)
- Ultraman (ウルトラマン Urutoraman Voice): Isao Yatsu (谷津勲 Yatsu Isao)
- Narrator (ナレーター Nareta): Akira Nagoya (名古屋章 Nagoya Akira)
- Alien Nackle (ナックル星人 Nakkeru Seijin): Naruse Masahiko (成瀬昌彦 Masahiko Naruse)
- Alien Nackle's Subordinates (ナックル星人の部下 Nakkuru Seijin no Kai): Hayami Hung (速水鴻 Hungu Hayami) & Sawa Mitsuru (沢美鶴 Mitsuru Sawa)
- MAT Headquarters Operation Room Officer (MAT本部作戦室係官 Matto Honbu Sakusen Muro kakarikan): Kiyoshi Yoshida (吉田潔 Yoshida Kiyoshi) & Toyoda Norio (豊田紀雄 Toyoda Norio)
- Doctor (医師 Isha): Tadashi Okuno (奥野匡 Okuno Tadashi)
Return of Ultraman Volume 10 Episodes 37-40.
- This is physically the last appearance of Ken Sakata's actor, Shin Kishida until his death on December 28, 1982.
- This is the final appearance of the original Aki Sakata, since an alternate one who didn't die appeared in the 2008 film Great Decisive Battle! The Super 8 Ultra Brothers.
- Stock footage from the episodes, "Terror of the Tsunami Monsters, Tokyo's Big Pinch", "Terror of the Two Tsunami Monsters, Tokyo's Dalong Reel", and "Ultraseven Arrives!" are used when Ultraman Jack fights the revived Seagorath and Bemstar.