Ultraman Day is an annual event celebrating the debut of Japanese tokusatsu science fiction television series Ultraman, which was created by Eiji Tsuburaya and produced by Tsuburaya Productions. Ultraman Day takes place every July 10th, the original air date of The Birth of Ultraman episode of the television series Ultraman, in 1966.

The Birth of Ultraman is the pre-pilot episode of the series Ultraman. Originally a stage show, the production was re-edited into an episode-like format. It originally aired on Japan News Network, owned by Tokyo Broadcasting System (TBS Television). The episode stars Susumu Kurobe as Shin Hayata, Akiji Kobayashi as Captain Toshio Muramatsu, Sandayu Dokumamushi as Daisuke Arashi, Masanari Nihei as Mitsuhiro Ide, Hiroko Sakurai as Akiko Fuji and Akihide Tsuwaza as Isamu Hoshino.

To coincide with the 2021 inaugural edition of Ultraman Day, an international event called Ultraman Connection Live: Ultraman Day was held through Ultraman Connection Live, an international virtual fan event surrounding the Ultraman fandom. Hosted Sean Nichols – an actor who plays Sean White in the Ultraman Max TV series – the inaugural event featured three actors from the original Ultraman show, including: Susumu Kurobe, Hiroko Sakurai and Bin Furuya.