Rigelian
The Rigelians were a warp-capable humanoid species who inhabited the planet Rigel V. ()

Physiology 

Rigelians were believed to have four or five genders, according to information obtained by Doctor Phlox. ()

They are known to have shared a similar internal physiology with Vulcans and Romulans. These similarities, notably to Vulcans, included similar blood chemistries. Rigelians also shared a similar neurology to Vulcans and Romulans, as they too were susceptible to the neurological disease known as Tuvan Syndrome. (; )

One of the ancestors of a Human corpse from the 31st century was discovered by Dr. Phlox to be a Rigelian, based on the individual's nucleotide sequence in his DNA. ()

History and politics

Relationships with other species 
During the 22nd century, Rigelians maintained relationships with several Alpha and Beta Quadrant species. By the 2150s, it was not uncommon to find a Rigelian visiting Earth.

In 2154, an Andorian and two Rigelians were attacked on Earth in a wake of xenophobia after the Xindi incident. ()

Later that year, three Rigelians visiting Earth, who were working for the Klingons, attacked and kidnapped Dr. Phlox from the streets of San Francisco. They later transferred him via a  to a Klingon ship. The Rigelian kidnappers and their ship were later destroyed. ()

In 2154, a Rigellian scoutship fell victim to an attack by a Romulan drone ship which disguised itself as Earth starship  in order to destabilize the sector. Recognizing the vessel, the Trade Commission contacted Starfleet to demand compensation for the loss of their vessel and the arrest of Enterprises commanding officer, Captain Jonathan Archer. ()

In early 2155, the Rigelians participated in talks discussing their wish to join as a possible member in the Coalition of Planets along with Humans, Tellarites, Andorians, Coridanites, Denobulans, and Vulcans. () During the negotiations, six of the Earth universal translators experienced a "glitch" and started confusing the Rigelian language with Andorian. ()

Trade and commerce 

Rigelian commerce was regulated by the Rigellian Trade Commission during the 22nd century. ()

The Rigelians independently operated their own freighters during the 24th century. In 2369,  docked at Deep Space 9 prior to its mission to the Gamma Quadrant. ()

Medical achievements 
Rigelians were responsible for developing a unique gene therapy technique that was capable of curing medical conditions such as Taggart's Syndrome. ()

During the mid-2260s, an experimental chemical stimulant designed to speed up reproduction and replacement of blood in the bodies of certain species was developed and successfully tested on Rigelian test subjects on the planet Rigel V. Although the side-effects included tremendous strain on the spleen and the liver, it was later discovered by Doctor Leonard McCoy to be a viable treatment for producing Vulcan T-negative blood. ()

People 
Named
 Drew Prachett

Unnamed
 Unnamed Rigelians

Appendices

Appearances

Background information 
The species name was spelled both as "Rigelian" and "Rigellian" in scripts, but in those few episodes in which they appear, the same make-up was used regardless of spelling. The name Rigellian was also given by behind the scene sources to a turtle-like species developed for a crowd scene in .

The homeworld of the Rigelians has not been firmly established, but it is known from  that Rigelians were at least present on Rigel V in the mid-23rd century.

A note in the final draft script of  described Rigelians as "an often mentioned, but never-before-identified species."

Apocrypha 
The Rigelians are a playable species for the Federation in the game Star Trek Online.

The   establishes that there were three species of Rigelians. These included:

 The Chelons, a species of tortoise-like reptiles native to Rigel III. These were the Rigellians from .
 The Jelna, humanoids native to Rigel V. They had four sexes and were the first Rigelian species to achieve spaceflight. These were the Rigelians seen in  and Star Trek Online.
 The Zami, humanoids native to Rigel IV, but who had also colonized Rigel V. They resembled Humans with slightly pointed ears and had a biochemistry similar to Vulcans. These were the Rigelians mentioned in  and . The Kalar were a racial group native to Rigel IV alongside the Zami before they were forcibly relocated to Rigel VII.

All Rigelian species were politically united and the Rigel system was considered to be a crowded and bustling population center in the novels, with its three native species and numerous colonists from other species.

External link 
 

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Species