Eternal is a game mode used in Katamari Damacy, and later in Beautiful Katamari. In the Make a Star 4 and 8 , and Make the Moon stages, if the level is completed with a large enough Katamari, the Eternal mode for that level will be unlocked once the game has been beaten at least once.

As its name suggests, Eternal has no time or size limits and is more of a Sandbox than anything. The level is otherwise the same, with the same size Katamari at the start of the stage, in the same location, and with the same objects available. Once the level starts, the player is allowed to play as long as he or she wants.

However, there are limits to Eternal stages. Each stage has a finite number of things that the Katamari can collect, and eventually, there will be nothing left to roll up. Eternal 1 can only get about 3 meters, Eternal 2 about 30, and eternal 3 has a limit of around 830 878 meters once all objects have been rolled up. Eternal was not included in We ♥ Katamari, but the Snowman stage was very similar, having no size goal or time limit.

In Katamari Damacy, Eternal stages will switch songs randomly when the Katamari reaches a size that requires a content load.

Eternal stages in Beautiful Katamari and Me & My Katamari are very similar to those in Katamari Damacy, in that they must be unlocked by having a large enough Katamari at the end of the stage. However, there is also the requirement of having a 100% rating on the level, in size, speed, and composition of your Katamari. Eternal stages are available on all levels, so long as a 100% rating is achieved. Unlike Katamari Damacy, however, Beautiful Katamari does not keep a record of your biggest Katamari in Eternal, nor do you receive a new celestial body.