Ultra Boy (Jo Nah) is a superhero appearing in DC Comics, primarily as a member of the Legion of Super-Heroes in the 30th and 31st centuries.

His real name is derived from the Biblical figure Jonah, who also survived being swallowed by a "large fish" (often interpreted as a whale).

Ultra Boy has made limited appearances in media outside comics, with James Arnold Taylor voicing him in Legion of Super Heroes (2006).

[6] Following Zero Hour: Crisis in Time!, which reboots the Legion's continuity, Ultra Boy is reimagined as the former leader of the Emerald Dragons gang and a member of Workforce.

[7] In Doomsday Clock, Doctor Manhattan erases Ultra Boy and the Legion from existence before Superman convinces him to restore them.