A Galaxy is a system of stellar matter including stars, planets, meteors, nebulae and other interstellar debris that is contained within a self-sustaining gravitational field. In short, it's where we keep all of our cool stuff and it doesn't go floating off into nowhere. Galaxies come in all shapes and sizes; the most common of which are elliptical galaxies, spiral galaxies and of course, your oddly-shaped blob-like irregular galaxies.
Galaxies contain varying numbers of star systems, star clusters and types of interstellar clouds. In between these objects is a sparse interstellar medium of gas, dust, and cosmic rays. Observational data suggests that supermassive black holes may exist at the center of many, if not all, galaxies. They are thought to be the primary driver of active galactic nuclei found at the core of some galaxies.
Known Galaxies Edit
Milky Way Galaxy Edit
- Main article: Milky Way Galaxy
The most important galaxy of note is naturally the Milky Way Galaxy, which some believe is named after a popular candy bar. The Milky Way is by far the coolest of all known galaxies, chiefly because it's where we all live. Plus the food is pretty good there. In terms of speculative fiction, all media that takes place on Earth is naturally taking place in the Milky Way Galaxy as well. Many science fiction vehicles also take place in the Milky Way, and often include fictional worlds and star systems.
In the continuity of Star Trek, the Milky Way is enveloped by an intense field of energy, which has come to be known as the Great Barrier. Penetrating the barrier is nearly impossible and though people have tried to send probes inside of it to analyze the barrier - none have ever returned. A Vulcan radical named Sybok believed that the mythological "Eden" known as Sha Ka Ree existed beyond the clouds of the Great Barrier. In the year 2287, Sybok kidnapped the crew of the USS Enterprise-A and forced them to pilot the ship through the Great Barrier in the hopes of finding Sha Ka Ree. Finding Sha Ka Ree turned out to be a fruitless endeavor, but they did succeed in penetrating the barrior. 
Andromeda Galaxy Edit
- Main article: Andromeda Galaxy
The Andromeda Galaxy is a spiral galaxy approximately 2,500,000 light-years away from Earth in the constellation of Andromeda. It is the nearest spiral galaxy to our own, the Milky Way. As it is visible as a faint smudge on a moonless night, it is one of the farthest objects visible to the naked eye. Like the Milky Way, the Andromeda Galaxy has satellite galaxies, consisting of 14 known dwarf galaxies. The best known and most readily observed satellite galaxies are M32 and M110.
The Andromeda Galaxy played a provincial role in the 1961 A for Andromeda television series. Scientists Doctor John Fleming and Ernest Reinhart discovered a radio signal being transferred from the Andromeda Nebula to Earth, carrying with it, instructions on how to construct a supercomputer. 
In the continuity of the Marvel Comics' Marvel Universe, the Andromeda Galaxy is home to the Shi'ar Empire. The throneworld of the Shi'ar is a planet called Chandilar, which is the birth place of the ruling Neramani family.
Star Wars Galaxy Edit
- Main article: Star Wars Galaxy
The Star Wars Galaxy refers to the setting featured in the Star Wars mythos. With few exceptions, nearly all characters, locations, organizations and items featured in the various Star Wars-related media takes place within the Star Wars galaxy. it is often referred to as a "Galaxy far, far away" or GFFA for short. Although the setting was first introduced in the original 1977 film Star Wars, the first coherent visualization of the galaxy from the outside perspective was seen at the end of Star Wars Episode V: The Empire Strikes Back.
Empirical Galaxy Edit
- Main article: Empirical Galaxy
The Empirical Galaxy is the primary setting of the Dreadstar family of comic book titles. The Galaxy is divided between the forces of the Monarchy and the Instrumentality - two rival authoritative bodies who have been waging a war against one another for the past two-hundred years.