Xeelee

The Xeelee are a fictional alien species appearing in the science fiction works of Stephen Baxter. They are an ancient and powerful race, primarily known for their role in the Xeelee Sequence, a series of novels and short stories that explore vast cosmological themes and humanity's place within them. The Xeelee are depicted as being incredibly advanced, having existed for billions of years and having witnessed the birth and death of stars and galaxies. Their motivations and biology are often enigmatic, and their presence in the universe is associated with massive, cosmic-scale engineering projects.

One of the defining characteristics of the Xeelee is their profound influence on the universe's development. They are shown to be capable of manipulating spacetime and constructing Dyson spheres and other megastructures that span entire star systems or even galaxies. Their history is intertwined with that of other cosmic entities, and they have engaged in long-standing conflicts and alliances that shape the fate of civilizations. Humanity's encounters with the Xeelee are often pivotal moments, forcing humanity to confront its own limitations and the sheer scale of the cosmos. The Xeelee represent a level of existence far beyond human comprehension, serving as a cosmic backdrop against which human struggles for survival and understanding unfold. Their ultimate goals and origins remain largely mysterious, adding to their awe-inspiring and sometimes terrifying nature.