Yassim was a Bajoran Vedek in the 2370s.
In 2374, while the Dominion was occupying Deep Space 9, Vedek Yassim organized a demonstration on the Promenade in opposition to the Dominion, claiming that they were evil, and Bajor should not ally with them. Major Kira Nerys decided she would talk with Yassim, hoping to stop the demonstration as that would be all Gul Dukat needed to increase security on the station and suppress the Bajorans further.
Yassim met with Kira, who tried to convince the Vedek not to protest, saying that it would only make things worse for Bajor. But Yassim was firm, citing that the Prophets say evil must be opposed. She questioned Kira on what she was doing to oppose the Dominion, to which the major replied that the Dominion presence was different from the earlier Cardassian occupation. Yassim disagreed and accused Kira of having become an apologist for the Dominion.
The next morning, Jake Sisko received a message from Yassim saying the protest would start at exactly 1400 hours. Kira, Jake, and Constable Odo waited on the promenade with Kira willing to arrest Yassim and other demonstrators. No one seemed to attend the demonstration, but then Yassim appeared on the upper promenade level and exclaimed "Evil must be opposed", before she stepped off the second level with a rope around her neck, hanging herself.
Her suicide greatly affected Kira, who realized she had indeed become a collaborator, people she had despised during the Cardassian occupation. She thus decided to start a resistance together with Odo. (DS9: "Rocks and Shoals")
Yassim was played by Lilyan Chauvin and stunt doubled by Leslie Hoffman.
Regarding Yassim, Ronald D. Moore commented: "I was thinking of the Buddhist monks who immolated themselves in Vietnam in the 1960s. The analogy isn't perfect (so don't look to link up the two political situations) but the dramatic political statement of a religious leader committing suicide in a public place was definitely one of the sources of inspiration for this episode." (AOL chat, 1997)