-Dave Lister ("Out of Time")
The Milky Way Galaxy was the location of Earth, the homeworld of humans and the Space Corps. The JMC mining spaceship Red Dwarf spent three million years drifting around the Galaxy after the accident which killed all but one of it's crew.
Later, Dave Lister would emerge from stasis to find that Red Dwarf was in the further out, uncolonised regions of the Galaxy - Deep Space - and he was, apparently, the last human alive, and this was hostile space inhabited by many nasty beings such as GELFs and rogue droids, the legacy of the human race.
Earth, the homeworld of humans, was located in one of the spiral arms of the Milky Way Galaxy. From the 22nd century onward, the Space Corps had spread out first along Earth's Solar System (see Jupiter Mining Corporation), and then further out among the stars.
The Space Corps had colonised many of the S3 planets - or terraformed many non-S3 planets and moons - in the local Galactic vicinity of Earth. With them, the Space Corps had brought genetically-engineered lifeforms (GELFs), and also artificial lifeforms, such as mechanoids and Simulants.
The toughest prison in the Galaxy was on Adelphi 12. The JMC mining spaceship Red Dwarf sometimes transported criminals to Adelphi 12 in it's brig. The greatest hero and legend of charted space was Ace Rimmer, who was worshiped by tribals on the moons of Venus.
Although alien life was never encountered, many species of GELFs and droids would take root in these regions long after mankind itself had since disappeared, and was presumed extinct, ensuring a lasting legacy for mankind, as well as a few enduring holograms.
Accordingly, some regions of Deep Space were now referred to as the "GELF Zone" ("Emohawk"), or "Rogue Simulant Hunting Country". ("Gunmen of the Apocalypse") The gang from Red Dwarf spent Series VI and VII extensively exploring Deep Space aboard Starbug, as they hunted for their stolen mothership.
As well as Red Dwarf, Deep Space was also explored by the Infinity Patrol, and three million years later was still patrolled by Space Corps External Enforcement Vehicles. Post pods still tracked ships in Deep Space to deliver mail to them.
When the crew of the JMC mining spaceship Red Dwarf were killed in an explosive radiation leak, the ship was left to drift out into Deep Space. Only one person survived - Dave Lister - who was in stasis at the time of the disaster. The ship drifted around the Galaxy unmanned for three million years, during which time the increasingly senile ship's computer Holly maintained the ship with the help of the Skutters. During this time, the descendants of Lister's pet cat, safely sealed in the hold, evolved into Felis sapiens. Most of this species left Red Dwarf on the Cat Arks to explore the Galaxy for Fuchal, leaving The Cat behind on Red Dwarf, a decade or so before Lister came out of stasis. ("The End")
During his time floating around the Galaxy in Red Dwarf, Holly attempted to compile a "comprehensive and definitive A-to-Z of the Known Universe, with street names, post offices, and little steeples and everything". However, these detailed star-charts were deliberately erased, along with four days worth of Holly's memory (and among other things) all in an unsuccessful attempt to cover up a rather sad incidence for Rimmer. ("Thanks for the Memory", Series II)
The gang from Red Dwarf have occasionally come across other humans, but the meetings haven't lasted long and Lister remains the last human in existence. In the last episode of Series X, the gang came into possession of the Galactic map - which contains all the surviving locations of note in the Galaxy - although use has yet to be made of it, since the Simulant Generals were also looking for it, resulting in a battle. ("The Beginning", Series X)
- The nanobots spent centuries exploring a new Galaxy in Lister's dirty laundry basket.
- The original lyrics to the Red Dwarf Theme by Howard Goodall before being rewritten included lyrics about the Milky Way Galaxy.
- Another Galaxy, the Andromeda Galaxy, is featured in the Red Dwarf novel Last Human by Doug Naylor, which is visited on a terraforming mission by the Mayflower.