Xee Lee

A mysterious, immensely powerful alien race whose activities form the backdrop for several novels by Stephen Baxter. They never appear on-screen, although their technology is frequently adapted for human use. The most famous example of this is The Xeelee Flower?; see also Night Fighters?, and rings of strange material thousands of light-years across rotating at the speed of light. That's what I call Real Ultimate Power.

The books featuring the Xee Lee are known collectively as the Xeelee Sequence.