The Interstellar Alliance (ISA or IA) was a political and economic alliance formed on December 30th, 2261, comprising many of the former League of Non-Aligned Worlds in addition to the major powers such as the Minbari Federation, Centauri Republic, Earth Alliance and Narn Regime.
The Interstellar Alliance is governed by a President whom is nominated by the ruling council and is confirmed by all the member worlds of the alliance. It is unclear as to the length of the term of the President of the Alliance, or whether there are limits to the amount of times one person may hold the office of President. There are only two known Presidents of the ISA.
It should be noted that the member worlds retain their own governments and leaders, such as the Earth President and the Centauri Emperor, and the Interstellar Alliance President is not in a position of direct command over their internal affairs. The ISA concerns itself with matters of diplomacy, trade, exploration, humanitarian aid, and defending against piracy and hostile powers.
ISA President John Sheridan was based on Babylon 5 until September of 2262, when he took residence in the headquarters that had been constructed on Minbar over the course of that year.
The Advisory board for the Alliance is made up of three senior representatives, including the Vice President. The original IA Advisory Board consisted of Ambassadors Londo Mollari, G'Kar and Delenn.
The Ruling council of the alliance is composed of ambassadors of the major powers of the alliance, and as such originally was composed of the ambassadors from Minbar, Narn and Centauri Prime. However as Delenn served both as the Minbari ambassador and Vice President of the alliance it is unclear whether or not the Vice President would also sit on the council. With the Centauri withdrawing from the Alliance in 2262, the council is now composed of the President, Minbar’s representative, Narn's representative, and Earth's representative. The council acts as a cabinet to the president advising him on events. Their other main role is nominating a new candidate for President when the current one decides to leave office.
Soon after the formation of the Alliance, it became clear that the Alliance needed an organization to keep track of what the various races were doing, and keep track of what threats there were to the new alliance. President Sheridan selected former Babylon 5 Chief of Security Michael Garibaldi to form and head up this new organization. Garibaldi had resigned by the end of 2262 due to his drinking problem. He was succeeded by Tessa Holloran, former leader of the Mars Resistance
Since the inception of the Alliance, the Anla'Shok (English translation: Rangers) have been a vital part of it, acting both as the ISA's police force and military. The leader of the Anla'Shok reports to the IA President, directing the Rangers per the President's orders.
The primary fleet of the ISA is the White Star Fleet. Towards the end of 2262, President Sheridan entered into an agreement with Earth to build a fleet of new destroyers based on the White Stars, later leading to the Victory class destroyers, which were crucial in finding a cure for the Drakh plague when it was released on Earth in 2267. Currently, the ISA's presidential liner is a Valen Class Cruiser.
At its formation, membership in the Alliance was offered to every major power, as well as to all members of the League of Non-Aligned Worlds. Before becoming fully-fledged members, each member must agree to abide by and uphold the Alliance's Declaration of Principles. Each member world has assigns an ambassador to the Alliance, where they act as a legislative body who may demand explanations and other actions from the President of the ISA.
- The Minbari Federation
- The Earth Alliance
- The Narn Regime
- The Centauri Republic (Withdrawn in 2262, liberated from the Drakh and rejoined in 2278)
- The Abbai Matriarchate
- The Brakiri Syndicracy
- The Drazi Freehold
- The Gaim Intelligence
- The Grome Marga Chulda
- The Hurr Androma Republic
- The Hyach Grand Council of Elders
- The Llort Mi-Ma-Ti
- The pak'ma'ra
- The Ventuki Conglomerate
- The Yolu Ingyo
- The Enphili
The ISA is a rather liberal organization, as they respect their member worlds' rights to freedom of speech, travel and religion. These rights are demonstrated in this prototype of the final declaration of principles. After this declaration was signed unanimously, G'kar, the author, produced another, better version.
The roots of the Interstellar Alliance grew out of Human (mostly those working on Babylon 5) and alien cooperation against the Shadows. At first, the two shared intelligence, formed joint military operations and employed telepaths (mostly non-humans, due to the affiliations of the human Psi Corps) to disrupt Shadow technology. Afterwards, when the aliens began to be less cooperative or flexible about working together, Sheridan began taking extraordinary steps  to get them to demand White Star protection of their respective frontiers. This along with a later agreement to join forces against the increasingly hostile Earth Alliance, set the stage for a new alliance of worlds to which Earth joined.
In its first year, the Alliance was beset with the problem of holding together races that were normally used to suspecting and competing with each other, along with other problems ranging from the sharing of technology to trade. But the new government's greatest first-year trial started with something relatively minor: attacks by parties unknown on shipping from worlds belonging to the Alliance. Originally believed to be the work of Raiders,it was soon discovered that the Centauri were behind the attacks, and war soon broke out. Although relatively brief, the war caused severe damage, resulting in the Centauri withdrawing from the ISA for almost two decades. In 2267, the ISA provided the Earth Alliance with the Excalibur to help find a cure for the Drakh plague somewhere in deep space.
The Interstellar Alliance survived and fulfilled its duties for well over one million years after its formation, with the names of all major players in the ISA's creation remembered and even revered throughout this time. By this time the ISA had achieved mastery over organic technology, with some of its member races evolving beyond the need for physical bodies, becoming beings of pure energy similar to the Vorlons.