Sejeel was a Vorta sent to the Alpha Quadrant during the Dominion War.
In 2373, Sejeel was sent with a Jem'Hadar unit to take the primitive, but strategically located world of Illarh. The Illarhi allowed Sejeel and his Jem'Hadar to stay and establish a communications post without a fight. Sejeel immediately settled into a luxurious residence, who's owner had been expelled. On his third day on Illarh one of Sejeel's servants, Draz, mentioned one of his dreams which fascinated the Vorta who couldn't have dreams himself. Every morning afterward the Vorta would listen to Draz's dreams. Then one morning Draz revealed himself to be a Starfleet officer when Starfleet forces under Jean-Luc Picard removed the Jem'Hadar. (STA - Tales of the Dominion War short story: "What Dreams May Come")