|Home world:||Planet Earth, Antarctica|
|First appearance:||The☆Ultraman Episode 1 "Birth of a New Hero" (1979)|
Subtitle: Frozen Monster (冷凍怪獣, Reitō Kaijū?)
- Height: 73 m
- Weight: 62,000 t
Shortly after the Scientific Defense Guard had been assembled, ice burgs from the Antarctic region began to melt with one of them containing ancient monsters known as the Seagras. An ice burg containing a lone Seagra was intercepted by the Scientific Defense Guard only for it to hatch from its icy tomb within minutes. After a laser barrier failed to contain the monster, Seagra made his way toward an unsuspecting harbor before completely freezing it and the city it was in, completely turning it into an icy tundra. The Scientific Defense Guard attempted to fight off using their fighters only for three more members of his species to emerge from the ice to assist it. Once Choichiro's fighter crashed he used the Beam Flasher for the first time to transform into Ultraman Joneus. As the Scientific Defense Guard was caught by surprised, Joneus took the monsters on one by one and shortly into the fight managed to cause to of them to freeze each other. The other two Seagras teamed up on him with his color timer beginning to turn red, forcing him to use his Planium Beam on both of them, knocking them out and returning the monster to their frozen confinements.
- Red King was originally supposed to appear in Seagra's place, but this was changed during production.
Powers and Abilities
- Adept Swimmer: Seagras can swim at medium speeds while in water.
- Icy Breath: Seagras can exhale icy breath capable of freezing an entire area within seconds.
|The☆Ultraman Kaiju & Seijin|
|Seagra | Spiral | Wanigodon | Red Smogy | Tough Gillan | Tough Gillas | Tough Gillaco | Firebadon | Combugon | Robot No.101 | Alien Baltan IV | Mikonos | Dolfiego | Xalome | Hectore | Liquid Monster | Opt | Garadoras | Xyclon | Gellon | Gadon | Goglan | King Moa | Badan | Islanda | Gerada | Janyur | Bedoran | Bader Group | Bagon | Janyur III | Zaanmoth | Zanba | Dragodos | Death Balan | Gibaaroga | Red King | Aboras | Banila | Earthtron | Ghostron | Gokinezula | Alien Baladon | Dabaran | Jadan | Jagon | Skeldon | Garbados | Megasaura | Babilar | Gamiba | Imedo Being | Goadarion | Jinario | Groteng | Plazoon | Agujon | Deathpower | Zuma | Gurol | Darantulas | Alien Noa | Heller | Roygar | Panther | Heller Army | Gumons | Hell Cat | Orolan | Gilos | Gilo | Fake Ultraman Joneus | Hatari | Large Battleship | Dostony | Spader | Caperadon | Alien Scien | Golding | Gedon | Hella Umaya | Heller Fleet | Makdatar|