Otrin's species were a humanoid species native to an unspecified planet located the Delta Quadrant. Their planet was a peaceful one, on the path to advancement when an Earth probe, Friendship 1 from across the galaxy entered their atmosphere. It told them about the Humans, about how to communicate, and about how to build antimatter and warp technology.
Prior to this incident, this species had no idea that antimatter existed. One of the early experiments with such particles resulted in a massive antimatter explosion, polluting the once M-class atmosphere with poisonous gas and radiation. Many of the planet's natives were killed, and the few that survived were forced to live in underground caverns that partially protected them from the radiation.
In 2378, they made face-to-face contact with Humans from the Federation starship USS Voyager, who were sent to retrieve the probe. Their leader, Verin, tried to get Captain Janeway to relocate them to a new home in exchange for her captured officers, members of an away team sent aboard the Delta Flyer. Janeway tried to cooperate with Verin until he killed Lieutenant Joe Carey.
After the two other hostages were returned, Janeway was convinced by Lieutenant Tom Paris and Neelix to help them restore their planet and neutralize the radiation. With assistance from a leading native scientist, Otrin, Voyager was able to restore the skies of their homeworld and neutralize the radiation. (VOY: "Friendship One")
This species was unnamed in the final draft of the episode's script, which simply described them as "aliens". For various reasons the name of the species was identified in the Star Trek Star Charts as the "Uxali"; a name that was later adopted for use in the It's A Wrap! sale and auction and at StarTrek.com.