Meta was a primary antagonist of the Star Trek: Deep Space Nine novel The Siege.
Meta was a shape shifter and apparently a member of either the same species as Odo or a similar species. It was unknown in he was one of the 100 infants sent out to explore the galaxy by the Founders, an insane Founder, or something else entirely.
By the mid 24th century Meta worked as an assassin for hire. The Ferengi Glav hired him to kill Quark, who had cheated him in earlier business dealings, and brought him on to Deep Space Nine in 2369.
Meta then began a campaign of terror against the residents of the station, making it appear that a serial killer was loose on DS9. The plan was that he would kill a few people, kill Quark, kill a few more people, then leave. The command staff soon realized they had another shape shifter on their hands and began working to try to isolate and capture him, a task made more difficult given the level of skill Meta demonstrated.
Odo realized what was going on. Disguising himself as Quark he confronted Glav in his quarters, and got Meta to reveal himself. Meta then killed Glav as he was bored with the individual. He tried to bribe Odo by offering to reveal where he came from along with ways to improve his shape shifting abilities, which Odo declined.
The two shape shifters began a battle to wear each other down by assuming a large number of shapes in the hopes that they could exhaust the other. Eventually the two wound up outside the station, continuing to fight each other as they drifted closer to the Bajoran wormhole.
Meta was soon sucked in to the wormhole. The wormhole reduced him to his constituent molecules, which were expelled into the Gamma Quadrant. It was a fate worse than death as all of his constituent molecules still retained some awareness. However he did not experience final death nor did he have any hope of ever being able to reassemble his body. Odo was rescued by the Deep Space Nine crew before the wormhole could claim him.