Memories of Babylon 5: Space Adventurers from J.Michael Stracznski

The Babylon 5 series was called a "novel in space" by many because of the deep complexity to the series (Wikipedia). From the outset, it was going to be an epic. I wasn't onboard initially, as science fiction epics had been done to no end in Star Trek and Star Wars, but I found myself addicted once I started watching.

The whole plot behind Babylon 5 was centered around a space station at a critical juncture between different empires of the universe. It made friction and constant conflict a major point of the series, as rivalries between different alien races was prevalent.

The majority of the aliens were humanoid (meaning they walked upright, and looked close to human in other physical characteristics). The major races were the Humans, Minbari, Narn, Centauri, and Vorlons. There were other minor races who would play a part, but the majority of the Babylon 5 storyline focused on these civilizations.

In the past, the Minbari had come conquering the human race, but, as the show told, stopped when they found out both races had connections.

The Centauri and the Narn were in constant war for the majority of the Babylon 5 series, creating conflicts between their ambassadors on the Babylon 5 station.

Of all these races, the least was known of the Vorlons, who only a selective few humans ever had contact with. According to Wikipedia, the Vorlons were on of the first sentient races in the universe.

One major race not cited there are the Shadows. This race provided a key point for the series, moving away from the stories on the station for an interstellar war that would consume many races.

The leader of the Babylon 5 station was initially Jeffrey Sinclair, but he was replaced by the experienced Captain John Sheridan (played by Bruce Boxleitner) by the second season. Sheridan lead Babylon 5 for the duration of the series, and played a key role in the interstellar war with the Shadows, as well as a revolution against the government of Earth.