Sea Dragon or seadragon may refer to:

• Leafy seadragon (Phycodurus eques)
• Phyllopteryx genus
  • Common seadragon or weedy seadragon (Phyllopteryx taeniolatus)
  • Ruby seadragon (Phyllopteryx dewysea)
• Glaucus atlanticus, a sea slug
• Thalassiodracon, a plesiosaur pliosauroid genus
• Thalassodraco, an ichthyosaur genus

• SSM-700K C-Star, a South Korean missile
• Operation Sea Dragon (Vietnam War), a military operation
• MH-53E Sea Dragon, a helicopter
• USS Seadragon, two ships of the US Navy
• Kairyū-class submarine ("Sea Dragon"), a class of Japanese submarines
• Blohm & Voss BV 138B, "Seedrache (Sea Dragon)", Luftwaffe's main long-range maritime reconnaissance flying boat
• Sea Dragon, China's People's Liberation Navy commando force

• Sea Dragon (rocket), a 1960s proposed American super heavy lift two stage sea launched rocket
• Sea Dragon (roller coaster)
• Sea Dragon-class ROV, a remotely operated underwater vehicle developed by China
• Sea Dragon (video game), is a horizontally scrolling shooter for the TRS-80 computer, written by Wayne Westmoreland and Terry Gilman, and released in 1982 by Adventure International
• Sea serpent, a mythical sea creature
• Seadragon, a zooming technology by Seadragon Software
• Sea Dragon, a fictional creature in the Majipoor novel series
• Sea Dragon Leviathan, an organism in Subnautica
• Ichthyosaur
• Francisco José do Nascimento (1839-1914), Brazilian maritime pilot and abolitionist known as "Dragão do Mar" (Sea Dragon)

• Sea Monsters (disambiguation)
• Dragonfish (disambiguation)
• Dragon (disambiguation)
• The Dragon in the Sea, a novel by Frank Herbert