The Xcathli are a humanoid alien species originating from Xcathlia. They are widely considered to be the most advanced documented species in the universe, having colonized hundreds of galaxies across the universe and universes beyond their home.
The Xcathli are about 190 cm (6' 2 51/64") on average for both men and women, although some records show some Xcathli long ago to have been over 250 cm tall (8' 2") and historical documents indicate that all Xcathli used to be taller. Their skin is tinged blue, and their eyes are always bright yellow. They have body proportions much alike a human's, with the exception of their large, pear-shaped heads.
The Xcathli originated from their home world Xcathlia. From there, they colonized the vast majority of their own galaxy, before turning their attention to the stars beyond. Forming the Intergalactic Confederacy in 8127, they quickly took control of most of the universe's trade. This was able to continue like this for some time, until the War of the Decamillenial Transition, which severely shifted the power dynamic and forced the Xcathli to back away from their position as intergalactic powerhouse.
Operations that involved interdimensional travel were first proposed in 21306, when Uir Forzannarte published Forzannarte's Second Theorem. This equation would become one of the most famous in history, as it paved the way for quantum compression and inter-dimensional fluctuation. In 21398, the Forzannarte I was sent beyond the Xcathli's home universe from a deep-space colony. The first reports returned on November 6, 21398, from a very similar universe. This universe was later known as X-002 (X-001 being the Xcathli home universe). Six months later, another operation was sent to the same universe, where a colony was established on a planemo in the distant reaches of the universe. The goal of the operation was to establish a colony that would not extend its influence over the home inhabitants, but simply provide a place for the Republic's citizens to live. This continued in five other universes over ten years. Now, the Xcathli have colonized and catalogued over 3,500 different universes, and have achieved interplanetary influence in almost 50 of them. The technology to create and destroy universes (Operation Lucid Dream) is in progress.