The Jem'Hadar are a dangerous genetically engineered race from the Gamma quadrant. Created and controlled by a race of shape-shifters known as the Founders, the Jem'Hadar are a race of warriors possessing absolute loyalty to their creators.

The Jem'Hadar take great pleasure in fighting other races and actually look forward to it. As a result, they are the most feared members of the Dominion, if not the entire Gamma quadrant and indeed much of the Alpha. The Dominion of which the Jem'Hadar are part of is a mighty planetary alliance and trading consortium within the Gamma quadrant, ruled by shape-shifting changelings known as the Founders, and administered and managed by the Vorta, ultimately defended by the Jem'Hadar.

The Jem'Hadar religion relies on the belief that the Founders are Gods due to their ability to create entire races and they therefore have no other purpose in life other than to serve their masters. The Jem'Hadar believe they are inferior to the Founders but also know, with equal certainty, that other races are inferior to them. The Jem'Hadar's loyalty to the Founders is at the core of their being and would not hesitate to kill anyone whom they see as the enemy.

The Founders have made the Jem'Hadar physically dependent on an enzyme known as Ketracel White, which they use to maintain superiority. Without the enzyme, the Jem'Hadar will begin to feel extremely sick and suffer pains throughout the body, similar to the side effects of an addiction to a drug. They need small amounts regularly to avoid such discomfort.

The Jem'Hadar have a pre-programmed basic intelligence and knowledge and an incredible ability to learn, able to speak within only a few hours of birth. Additionally, they have an ability to cloak themselves making an excellent camouflage, they needn't sleep nor eat, and there are no Jem'Hadar women.

Should a founder die, all Jem'Hadar responsible for his or her well being must commit suicide. All acts of disobedience are punished by death - immediately.