She was one of the leaders of a group of Skrreeans that came through the wormhole in 2370 to seek a new home. They were looking for Kentanna, the planet of paradise, which they believed was Bajor. (DS9: "Sanctuary")
Vayna was played by Betty McGuire.
The Star Trek Encyclopedia, 3rd ed., p. 428 incorrectly credits actress Kitty Swink for this role.
Her name comes from the script.