|Ixtana'Rax, a Gamma "honored elder" Jem'Hadar (2374)|
|Ikat'ika, a Gamma Jem'Hadar (2373)|
|Kudak'Etan, an Alpha Jem'Hadar (2374)|
- "As of this moment, we are all dead. We go into battle to reclaim our lives. This we do gladly, for we are Jem'Hadar. Remember: victory is life."
Jem'Hadar were generated in "birthing chambers." Their growth cycle was accelerated, such that they reached full maturity only three days after emergence. They did not mate, and so their species had no females. (DS9: "To the Death")
As infants, Jem'Hadar strongly resembled mammalian species, with a complexion resembling that of Humans; within a day of maturation, Jem'Hadar children already had advanced language skills and cognitive reasoning; as they aged, their skin paled to a bluish-white, and became scaly and reptilian in appearance. (DS9: "The Abandoned")
Adolescent Jem'Hadar required food for nourishment. (DS9: "The Abandoned") Adult Jem'Hadar did not require sleep, and their sole source of nourishment was the drug ketracel-white, which provided the Jem'Hadar with all necessary nutrients, as well as an isogenic enzyme that had been deliberately omitted from their metabolism. As a result, all Jem'Hadar were addicted to "the white," which was regularly distributed to them by Vorta overseers. This was the Founders' means of ensuring the Jem'Hadar's loyalty to them. (DS9: "To the Death")
Without a steady supply of white, Jem'Hadar suffered withdrawal symptoms: their circulatory systems began to shut down, beginning with muscle spasms. Psychologically, they became uncontrollably violent, attacking their enemies, then their Vorta overseers, and finally each other. (DS9: "The Abandoned", "Hippocratic Oath", "To the Death", "Rocks and Shoals")
Jem'Hadar were designed to have excellent vision and strength several times greater than Humans. (DS9: "Favor the Bold") They also had the ability to "shroud" themselves, a form of camouflage that acted as a personal cloaking field, effectively hiding them and their weapons from both sensors and the naked eye. (DS9: "The Jem'Hadar", "The Abandoned") However, they had to drop this effect when attacking. (DS9: "To the Death") Also, Jem'Hadar lost the ability to shroud when they were suffering withdrawal from the white. (DS9: "Rocks and Shoals")
Jem'Hadar had extremely resilient bodies, such that phaser beams on "stun" intensity had no effect on them. During the Dominion War, Federation fighters quickly learned that only lethal settings could be used to stop them. (DS9: "Rocks and Shoals")
After an enormous Jem'Hadar fleet was eliminated inside the Bajoran wormhole during Operation Return, the Gamma Quadrant was effectively sealed off from the Dominion forces in the Alpha Quadrant. The Dominion began to breed Jem'Hadar soldiers in the Alpha Quadrant known as "Alphas" in 2374. The Alphas' genetic and psychological profiles were designed specifically for combat in that Quadrant, and so the Alphas were regarded – largely by themselves – as being superior to original "Gamma" Jem'Hadar, so their introduction led to considerable friction with their Gamma Quadrant counterparts. The Founders believed this made them better leaders than the Gammas, though this opinion may have been revised after one of the Alphas' first missions, led by Kudak'Etan, became a disastrous failure. (DS9: "One Little Ship")
Psychology and lifestyle
Jem'Hadar were engineered to be soldiers and ship crews, and nothing more. Their culture shunned all forms of relaxation and recreation, on the belief that such things made them weak. (DS9: "To the Death") For the same reason, Jem'Hadar fighters, and probably other classes of Jem'Hadar starships, were not equipped with chairs. (DS9: "A Time to Stand", "One Little Ship")
Like the Vorta, the Jem'Hadar were genetically engineered to revere the Founders as gods and to be unquestioningly loyal to them. However, this engineering was not flawless, which is why it was necessary to make them dependent on the white. When a Jem'Hadar company assigned to a Dominion science team on Vandros IV rebelled, Dominion experts nervously predicted that they could gather support from other Jem'Hadar units in the Gamma Quadrant, and effect a complete takeover of the Dominion in less than a year. (DS9: "To the Death")
Most Jem'Hadar died young in battle; as such, it was rare for them to live past 15 years of age. Few ever lived to the age of 20, and those who did were awarded the title "Honored Elders." To date, no Jem'Hadar has ever lived to the age of 30. (DS9: "To the Death")
Culture and tradition
Although the Jem'Hadar worshipped the Founders as gods, the vast majority of the Jem'Hadar had never actually seen a Founder, and some doubted that they even existed. (DS9: "Hippocratic Oath") Yet they built their service to the shapeshifters into a religion, literally regarding the Founders as living gods, to the extent that the Jem'Hadar ritualistically committed suicide if they failed to protect a shapeshifter from harm. (DS9: "The Ship")
The Vorta, as the representatives of the Founders, were also given immense loyalty by most Jem'Hadar – even when such loyalty seemed unwarranted. Absolute obedience from the Jem'Hadar was further guaranteed by the Vortas' control of the ketracel-white. (DS9: "The Abandoned", "Hippocratic Oath", "Rocks and Shoals")
Although the glory of the Founders meant everything to the Jem'Hadar, they also showed a strong sense of honor for themselves. Ikat'ika, First of Dominion Internment Camp 371 showed this when he refused to kill Worf, even after he was ordered to by his superior Vorta. He chose rather to yield the fight than to kill Worf, saying "I cannot defeat this Klingon. All I can do is kill him, and that no longer holds my interest." He was ordered to be shot for this insubordination. This indicated that a Jem'Hadar might have preferred insubordination and therefore death to doing something he considered to be dishonorable (DS9: "By Inferno's Light").
Jem'Hadar combat units followed a very specific hierarchy. Normally, a Vorta commanded one or several units. Every unit contained a Jem'Hadar First, who was in command. Each Jem'Hadar after the First was also given a number rank (Second, Third, Fourth, etc.). In the event the First was killed, the Second took over for the First, the Third took over for the Second, and so forth. Although the succeeding Jem'Hadar assumed the duties of his superior, he only received the higher number rank if his Vorta commander granted it. (DS9: "Hippocratic Oath", "Rocks and Shoals")
Before each battle, the following ritual was observed by the Jem'Hadar:
- First: "I am [Rank] [Name], and I am dead. As of this moment, we are all dead. We go into battle to reclaim our lives. This, we do gladly, for we are Jem'Hadar. Remember - victory is life."
- Jem'Hadar: "Victory is life." (DS9: "To the Death")
When ketracel-white is dispensed, the following ritual exchange usually took place between the Vorta overseer and the ranking Jem'Hadar:
- Vorta: "[Rank] [Name], can you vouch for the loyalty of your men?"
- First (or ranking Jem'Hadar): "We pledge our loyalty to the Founders from now until death."
- Vorta: "Then receive this reward from the Founders. May it keep you strong." (DS9: "To the Death", "Rocks and Shoals", "Favor the Bold")
Jem'Hadar Firsts were also capable of distributing the white among those under their command. By 2374, Alpha Jem'Hadar no longer recited the ritual dispersal statement, as they believed they demonstrated their loyalty by their actions, not their words. (DS9: "One Little Ship")
Technology and equipment
- Uniforms: Jem'Hadar uniforms allowed their wearers to be almost completely unaffected by many forms of anti-personnel force field. (DS9: "The Jem'Hadar")
- Weaponry: Jem'Hadar carried plasma weapons in both rifle and pistol variants, capable of firing lethal disruptor bursts with anti-coagulants that were designed to slowly kill their enemies if the burst itself did not. The weapons had at least two other settings: they were able to stun, and to fire a more powerful burst capable of vaporizing a humanoid target. (DS9: "Tacking Into the Wind", "The Search, Part I", "The Ship", "Change of Heart", "By Inferno's Light")
- Melee Weapons: In close quarters, Jem'Hadar preferred the kar'takin. (DS9: "To the Death", "Sons and Daughters"). They also carried combat knives. (DS9: "To the Death", "The Siege of AR-558")
- "The Jem'Hadar" (Season 2)
- "The Search, Part I" (Season 3)
- "The Search, Part II"
- "The Abandoned"
- "Hippocratic Oath" (Season 4)
- "To the Death"
- "Broken Link"
- "The Ship" (Season 5)
- "In Purgatory's Shadow"
- "By Inferno's Light"
- "Ties of Blood and Water"
- "Blaze of Glory"
- "In the Cards"
- "Call to Arms"
- "A Time to Stand" (Season 6)
- "Rocks and Shoals"
- "Sons and Daughters"
- "Behind the Lines"
- "Favor the Bold"
- "Sacrifice of Angels"
- "Statistical Probabilities"
- "The Magnificent Ferengi"
- "One Little Ship"
- "Change of Heart"
- "Tears of the Prophets"
- "Image in the Sand" (Season 7)
- "Shadows and Symbols"
- "The Siege of AR-558"
- "'Til Death Do Us Part"
- "Strange Bedfellows"
- "The Changing Face of Evil"
- "When It Rains..."
- "Tacking Into the Wind"
- "Extreme Measures"
- "The Dogs of War"
- "What You Leave Behind"
- VOY: "Flesh and Blood" (hologram)
- When designing the look of the Jem'Hadar, makeup supervisor Michael Westmore was told to "design something that was tough, that they could shoot at but they couldn't hurt, they were indestructible, as an army they were unstoppable, and they would have thick skin." Westmore based the basic design on a rhinoceros skin, but also incorporated elements from dinosaur skin, and he has compared the top of the Jem'Hadar head to a triceratops. (Michael Westmore's Aliens: Season 5, DS9 Season 5 DVD special features).
- The sculptures for the Jem'Hadar were created by makeup artists Kevin Haney and Mark Shostrom.
- Two special effects face make-up lots for a Jem'Hadar was sold off on the It's A Wrap! sale and auction on eBay,   as well as a special effects gloves lot,  a prop pistol,  and a knife. 
- Ikat'ika is the only Jem'Hadar to appear in more than one episode of Deep Space Nine.