The
universe of
Known Space is the name for the
continuum in which much of
Larry Niven's fiction takes place.
It is characterized by a keen sense of how reality can be odd, and a lot of use of science fiction archetypical technology.
Populated by (at last count): Kzinti, Humans, Pierson's Puppeteers, Grogs, Frumious Bandersnatchi, Slavers (mostly dead), and other things, it contains the Ringworld, as well as a bunch of other wierd shit.