Baten Kaitos: Eternal Wings and the Lost Ocean is a role-playing video game developed by Monolith Soft and tri-Crescendo, and published by Namco, for the Nintendo GameCube. In it, the player assume the role of a "guardian spirit" – an unseen player avatar – who guides protagonist Kalas and his party of companions in an adventure across an aerial floating island-based kingdom in the clouds. The game is focused around the concept of "Magnus" - magical cards that capture the "essence" of items found in the in-game world. The concept is used as a plot device, for in-game item management, and as a basis for the card-themed battle system. The game was noted for its unique battle system, which included aspects of turn-based and action-based battle systems, collectible card games, and poker.

Developed specifically for the GameCube due to its lack of JRPGs in its game library, the game was generally well-received by critics, but received lukewarm sales. Despite this, a prequel, Baten Kaitos Origins was green-lit and released at the end of the GameCube's lifespan, receiving a similar reception itself.