In 2372, Omet'iklan was First of a unit under the Vorta Weyoun, whose attack ship was set upon by a group of rogue Jem'Hadar who had seized an Iconian gateway on Vandros IV. Omet'iklan and five of his surviving men were transported aboard the USS Defiant before their ship exploded.
Under Weyoun's orders, Omet'iklan reluctantly agreed to a joint mission with the Defiant officers to destroy the gateway on Vandros IV. Omet'iklan regarded the Vorta with contempt for their belief that the Jem'Hadar's loyalty can only be kept by deception and ketracel-white. Omet'iklan was a vicious disciplinarian who killed his Second, Toman'torax, for attacking Lieutenant Commander Worf. When Sisko refused to do the same to Worf, Omet'iklan promised to kill Sisko when the mission was over. As the mission progressed, Worf expressed his concerns over the threat the Captain had received. Worf even suggested that the Captain stay on the ship during the away mission which the Captain refused to do.
Consequently, Worf warned the Captain not to turn his back on his enemy. Worf went on to "reassure" the Captain that if Omet'iklan should kill him that Worf would make certain that Omet'iklan would not live long enough to boast about it to anyone. Captain Sisko, for his part, smiled slightly saying that he was "very comforted" at the idea. During the attack against the rebel Jem'Hadar, Sisko saved Omet'iklan's life, which surprised him. After they successfully accomplished their mission, Omet'iklan killed Weyoun for questioning his loyalty earlier by attempting to withhold the information about the gateway.
Omet'iklan did not carry out his threat to kill Sisko, but he did tell him that the next time they met it would be as enemies. He and his unit elected to remain on Vandros IV to hunt down the remaining rogue Jem'Hadar. (DS9: "To the Death")
Two years later, following the outbreak of full-scale war, Sisko recalled Omet'iklan's actions to Remata'Klan, whose unit had crashed on the same deserted planet, hoping to turn him against his treacherous Vorta, Keevan (who hoped to see the Jem'Hadar die before they ran out of white and killed everything in their path, including him) - he was unsuccessful, and Remata'klan was killed in a suicidal attack. (DS9: "Rocks and Shoals")
"If you're looking for your weapons, they were removed in transport."
"Even without weapons, we're more than a match for you."
- - Benjamin Sisko and Omet'iklan
"...the only thing I despise more than the Federation is a Jem'Hadar soldier who breaks his vow of allegiance."
- - Omet'iklan to Benjamin Sisko
"Are you accusing me of something?"
"It is not for us to accuse a god of betraying heaven. The gods themselves will sit in judgement over you."
"I'm no god, and neither are the Founders. The sooner you realize that, the better off you'll be."
- - Odo and Omet'klan, of Odo's opposition to the Dominion
"In battle, nothing is certain."
- - Omet'iklan
"You think you have to lie to us and use the white to ensure our loyalty. But the fact is, we are more loyal to the Founders than the Vorta ever will. It is the reason for our existence. It is the core of our being."
"There's an entire company of Jem'Hadar down on Vandros Four who would disagree with you."
"And for that, they will die."
- - Omet'iklan and Weyoun
"I threatened to kill you, but you were still willing to sacrifice yourself to save my life."
"Looks that way."
"If you have to ask, you'll never understand."
- - Omet'klan and Benjamin Sisko
Omet'iklan was played by actor Clarence Williams III.
The script for "To the Death" gives the pronunciation of Omet'klan's name as "oh-MET-i-klon". Of his first on-screen appearance, it goes on to describe him as, "...unimpressed, he is a consummate professional soldier who's been in combat his entire life. He's been in far worse situations than this one." 
Director LeVar Burton had Williams in mind to play the character from the start. "He's an old friend of mine, but we'd never worked together before." he explained. "This was just an opportunity to say, 'Hey CW, you want to come and do this thing?'" (Star Trek: Deep Space Nine Companion (p. 347))
Producer Ronald D. Moore really enjoyed Williams' take on the character; "I liked Clarence Williams III, I always have, and I thought he really personified the Jem'Hadar for the first time in a way that the audience could grab onto. The Jem'Hadar in a lot of the episodes tend to kind of bland out. Sometimes it's hard to differentiate between them, and [Williams] brought something to that performance that made him at least stand alone among that race." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p.120)
Similarly, Star Trek author Keith R.A. DeCandido wrote that Williams "knocks it out of the park as Omet'iklan." Of the character itself he opined, "Omet’iklan is the wise, ruthless leader, the brutal strategist, the loyal soldier—but his loyalty is to the Founders, not the Vorta, whom he holds in obvious contempt." 
In the Pocket DS9 novel Avatar, set in 2376, Ezri Dax thinks of Omet'iklan as an example of a mature and more disciplined Jem'Hadar when Elias Vaughn divulges information on some Starfleet research indicating Jem'Hadar became less violent and more disciplined as they age.
Omet'iklan is also featured in the Star Trek Customizable Card Game which describes him as a "steely disciplinarian".