Giant Robo: The Day the Earth Stood Still (ジャイアント・ロボ - 地球が静止する日, Jaianto Robo—Chikyū ga Seishisuru Hi) is a 1992–1998 OVA series based on Mitsuteru Yokoyama's manga series Giant Robo. It was written and directed by Yasuhiro Imagawa.

Giant Robo is a homage to Yokoyama's career. The series features characters and plotlines from the manga artist's entire canon of work, effectively creating an all-new story. The events take place in the near future, 10 years after the advent of the Shizuma Drive triggers the third energy revolution. The series follows the master of the titular Robo, Daisaku Kusama, and the Experts of Justice, an international police organization locked in battle with the BF Group, a secret society hell-bent on world domination.

The OVA is recognized for its "retro" style and operatic score. The character designs emulate Yokoyama's drawing style and the action setpieces are influenced by Hong Kong action cinema.

The first installment of the series, "The Black Attaché Case", was released on July 22, 1992. Originally intended to finish within 36 months, the seven-volume series was ultimately released over the span of six years. "The Grand Finale" was released on January 25, 1998. The OVA has since been translated into English, Cantonese, Dutch, French, Italian, Korean, Portuguese and Spanish.