The Vidiians are a civilization in the Delta Quadrant. The primary government of the Vidiian people was the Vidiian Sodality.

The Vidiians were once, as a whole, afflicted by a horrific degenerative disease known as the phage. Their entire technological base was centered around medicine and the prolongation of life, as their bodies failed and new transplants and procedures were required to keep them alive. Hostile portions of Vidiian culture became aggressive in the pursuit of new ways to stave off the phage, often harvesting organs from unwilling donors and performing horrific medical experiments on outsiders they encountered. (VOY episodes: "Phage", "Faces", "Deadlock", "Lifesigns", "Fury")

By the beginning of the 2380s, the Vidiians had rid themselves of the phage. (TNG novel: Q & A) Kurros of the Delta Quadrant "think tank" took credit for finding the cure, as he was explaining his creditals to Janeway. VOY episode "Think Tank"