(covers information from several alternate timelines)
The Yridians were a warp-capable race in the 24th century. They were regarded as information merchants and smugglers, and were generally considered devious and untrustworthy. (TNG: "The Chase"; DS9: "Facets")
Yridians were humanoids who were usually bald, others had black or brown curly hair. They had wrinkled skin. They also had large rodent-like pointy ears but small eyes and noses. All Yridians had an indented ridge running across the full length of their heads and extending down their nose. Most Yridians had no thumbs, and possessed only four fingers on each hand.
History and politicsEdit
It was not known if the Yridians had a central government. The Yridians encountered by the Federation appeared to be loosely aligned and concerned with their own interests, often serving as hired agents for other races and operating as groups or individuals. (TNG: "The Chase") They were often unwilling to reveal information they collect without payment. Despite their reputation, the Yridians were often seen on space stations and planets within Federation space. (TNG: "Birthright, Part I", "Gambit, Part I"; VOY: "Non Sequitur") However, the shady dealings of some Yridians earned them arrest warrants issued by governments such as the Klingon Empire (TNG: "Gambit, Part I") and their trading goods were often confiscated. (DS9: "Facets")
At some point before the 2360s, the Federation believed that the Yridian race went extinct. This disappearance was so total that it even convinced the Borg, who designate the Yridians as Species 6291, that the species was no longer in existence. However, Rudolph Ransom, a Starfleet exobiologist, discovered that there were some still alive and carried out First Contact. This act directly led to his promotion to the rank of captain. (VOY: "Equinox")
After this point Yridians were encountered throughout Federation space. A group of Yridians learned of the research of Dr. Richard Galen sometime prior to 2369. The Cardassian Gul Ocett purchased the information they had obtained, and the Yridians later attacked Galen's shuttle to steal further data. Their ship was destroyed by the USS Enterprise-D before it could return to the Cardassians with its findings. (TNG: "The Chase")
The Yridians were known to be targets of Maquis raids in late 2370 as Starfleet put together a Yridian convoy as lure for a Maquis attack. The convoy of six ships left Deep Space 9 for the Demilitarized Zone, destined for Cardassian space, carrying a supply of isomiotic hyposprays, plasma flares and quarantine pods. (TNG: "Preemptive Strike")
A Yridian called Paltriss created several rings, later known as the Rings of Paltriss. They became extremely valuable and, as such, were removed from the Yridian homeworld over time. In 2370, Quark came into possession of forty-two of them. (DS9: "Melora")
The Yridians exported several beverages to the Federation, Klingons, and Ferengi, including Yridian tea, Yridian ale, and Yridian brandy. (TNG: "Eye of the Beholder"; DS9: "The Sword of Kahless", "Who Mourns for Morn?")
The Yridians operated their own design of starship, used as both a destroyer and as a freighter. (TNG: "The Chase", "Firstborn") Others were known to operate small warp-capable shuttles. (TNG: "Birthright, Part I")
- "If Wishes Were Horses"
- "In the Hands of the Prophets"
- "The Sword of Kahless"
- "Sons of Mogh"
- "Rules of Engagement"
- "Body Parts"
- "The Assignment"
- "The Darkness and the Light"
- "In Purgatory's Shadow"
- "A Simple Investigation"
- "Business as Usual"
- "Ferengi Love Songs"
- "Call to Arms"
- "A Time to Stand"
- "Sons and Daughters"
- "Favor the Bold"
- "Who Mourns for Morn?"
- "In the Pale Moonlight"
- "When It Rains..."
Background information Edit
The conversation between Quark and Ashrock in "Melora" suggests that the Yridians do have a homeworld. It is likely Yridia, a world mentioned in "Lethe", as Yridia (β) has previously been established as the name of their planet in the DS9 novel Hollow Men.
According to the script for "Accession", the species name was pronounced as "yir-ID-ee-uhn". 
In Star Trek Online, the Yridians are a minor non-playable race. They are currently in game as opponents in a few missions, or as crew on the player's ship.