(covers information from several alternate timelines)
|Degra, a Xindi-Primate (2154)|
The Xindi (pronounced ZIN-dee) were an alliance of species who evolved on the same planet in the Delphic Expanse, known as Xindus, whose infamous attack on Earth and attempts to terminate Humans in the early 2150s changed the course of history and initiated the series of events that helped establish United Earth as a major interstellar power. In at least one future timeline, from where Daniels originated, the Xindi state had, by the 26th century, become a member of the United Federation of Planets.
Six different intelligent species developed on Xindus; one of them, the Xindi-Avians, was believed extinct by the 2150s. The surviving species were united under the governance of the Xindi Council, which contained two representatives from each species.
The different Xindi species were extremely similar in their functionally-important DNA, sharing over 99.5% despite the apparent physical differences. (ENT: "The Xindi") All the Xindi species shared distinctive ridges on their cheekbones and foreheads. (ENT: "The Xindi", et al.)
- Main article: Xindi history
The Xindi had a long and turbulent history, characterized by interspecies conflict up until the destruction of their homeworld in the 2030s. In the 2150s, they attempted to destroy Earth with a massive weapon.
The Xindi practically worshipped the Guardians, considering them saviors. Children were taught to revere them and give thanks to them at the end of each day. It was a terrible offense to question a Guardian. (ENT: "The Council")
The Primates, Arboreals, and Reptilians spoke a common language that was recognized by Starfleet universal translators. The Insectoids and Aquatics understood this language, but appeared to be physically incapable of speaking it.
Although a badly incinerated Xindi corpse appears in the second season finale "The Expanse", this effectively hid the fact that, by that point, no design for the physical appearance of the Xindi had been created. ("The Xindi" text commentary, ENT Season 3 DVD) Executive Producer Brannon Braga recollected, "In terms of who the Xindi were, that didn't come until after the break [between the second and third seasons]." ("The Xindi Saga Begins", ENT Season 3 DVD special features) Giving life to the Xindi, designing how they looked, took a total of about two months. (Star Trek: Communicator issue 149, p. 50) Commenting on the selection of the five specific species incorporated into the Xindi, Executive Producer Rick Berman stated, "They just were the ones that seemed right for us. It was just something Brannon and I developed; we knew that there was going to be the humanoids and the reptilians because we had touched on those, and then the other three came quite easy." (Star Trek: Communicator issue 147, p. 16)
Of all the guest stars and recurring actors who featured on Star Trek: Enterprise, former longtime Star Trek casting director Ron Surma cited the group of performers who played recurring Xindi as a highlight, enthusing, "I liked the Xindi guys [....] Those guys were a lot of fun." Surma also pointed out that Randy Oglesby, Rick Worthy and Scott MacDonald had all made repeated guest appearances on Star Trek before portraying recurring Xindi. 
With very little information available about the Xindi at the start of the third season (such as in the script for third season opener "The Xindi"), the overall design for the group was not set in stone. "We were creating it as we went along which is both liberating and limiting," offered Xindi-Primate actor Tucker Smallwood. "That sort of thing takes agreement. Our directors change each week. You don't necessarily have that continuity, as you go from episode to episode." Therefore, some of the actors who played Xindi Council members (including Scott MacDonald, Rick Worthy, Randy Oglesby and Smallwood himself) devised much about the multiple species, at least for personal subtext. Continued Smallwood, "[We] would interact each time we worked together–not only try to find continuity but also create, so that we had someplace to go to and come from." Much of this inventing was during the group's long hours in make-up. "We teased about our rituals and having to make stuff up," Smallwood reminisced. One thing the performers decided was that, though the only Xindi species to be firmly established as including females were the Aquatics and Reptilians (with the Insectoids being an asexual race), other Xindi females do exist. (Star Trek: Communicator issue 151, pp. 51 & 52)
CGI was used extensively to create some of the Xindi characters, with the Aquatics and Insectoids being depicted entirely with computer-generated figures. Visual Effects Producer Dan Curry recalled of the visual effects artists, "We were very excited–we felt that now technology and what we've learned would enable us to do better quality work than we had done in the past with these [all-CGI characters]." (Star Trek: Communicator issue 149, p. 50) "A few years ago it would have been financially impossible to do," reckoned Rick Berman, midway through the third season. "What has happened now is that we have the technology and the people who can give it to us. The problem is that with our two CG species, the Insectoids and Aquatics, we will probably not see as much as we would like because of the expense." (Star Trek: Communicator issue 147, p. 16)
Much research and development was invested in the character design for the Aquatics and Insectoids, at the start of the third season.  The CG artists were well-prepared for the challenge of visually creating the characters. Digital Effects Supervisor John Teska recollected, "I'd already heard that there was gonna be this race of Xindi that, of course, were going to be multiple different kinds of aliens. You know, we had heard that the Insectoids and the Aquatics were going to be CG." ("Visual Effects Magic", ENT Season 4 DVD special features) The process began, in both cases, with sketches by Dan Curry, prior to the CG artists developing these designs.  Eden FX co-founder John Gross remembered, "We worked on [the Xindi insectoids and aquatics] together [with FX artists David Morton, Sean Scott, and John Teska], modelling them and rigging them and getting them working. It took a few weeks." (Star Trek Magazine issue 118, p. 30) Additionally, other Xindi were occasionally represented with CGI, including some footage of the Reptilians in "Countdown". ("Countdown" text commentary, ENT Season 3 DVD) "And I think we've had [Xindi] sloths also," said Gross, "that have been [done in] CG [as opposed to actors wearing costumes and make-up]." (Star Trek Magazine issue 118, p. 32) Virtually all the clothing worn by the Xindi was designed by Bob Blackman; this even included ambassadorial robes worn by the Insectoids, though Insectoid armor (the only exception) was designed by Dan Curry. (Star Trek: Communicator issue 149, pp. 50 & 51)
The shipboard graphic layouts for the various different Xindi species were designed to resemble each other (at least, in the case of the Xindi-Primates and Xindi-Reptilians). However, each species was given a different color scheme; the Reptilians had primarily blue control graphics, whereas the Primates had green ones and the Insectoids' were colored red. ("The Xindi" text commentary, ENT Season 3 DVD) Production Designer Herman Zimmerman offered, "We did do a lot of very specific Xindi graphics and, within the larger framework of the Xindi, each Xindi species had their variation of those graphics." Under Zimmerman's aegis, the art department also had to design the look of the sets for each Xindi species. "That was a good challenge," said Zimmerman, "just because we had to make them different enough that you always knew where you were." (Star Trek: Communicator issue 151, p. 56)
Executive Producers Berman and Braga were highly proud of how the Xindi turned out. Braga remarked, "The whole Xindi species concept was really cool. That's a science fiction concept I'd never seen before. You had insects and aquatics with intelligence and culture. I thought that was a fascinating idea."  He further commented, "The five-specied Xindi is an interesting science-fiction concept that I think really worked out well. Each species was featured at some point along the way. They had internal strife. They're betrayed just like... They betray each other. It's like a Shakespeare play or something, backstabbing and all sorts of stuff going on." ("The Xindi Saga Begins", ENT Season 3 DVD special features) This duplicitous aspect of the Xindi's interrelationships was one of the group's many facets that Braga liked. "By the end the Xindi were a complicated, interesting and visually stimulating species," he opined. "I liked the way we gave each of the Xindi species its day in the sun, and even a sixth, extinct species got explored in a way." (Star Trek Magazine issue 117, p. 62) Shortly after Berman viewed the first completed shots of the Aquatics and Insectoids, he enthused of the footage, "It's far more than I expected. Considering the budget that is available to us, it's just spectacular stuff." (Star Trek Monthly issue 110, p. 15) He later raved about the various Xindi species, "I think they all look great." (Star Trek: Communicator issue 147, p. 16)
Those who approved of the Xindi also included visual effects artists. Character Animator Sean Scott referred to the Xindi as having been "an exciting addition" to the series.  Production illustrator John Eaves exclaimed, "The Xindi were a very fun race to draw for, and I so loved the costumes that Bob Blackman came up with for these nasty space demons!!!"  Dan Curry was also pleased with how realistic the CGI Xindi turned out. (Star Trek: Communicator issue 149, p. 50)
Despite their success, the Xindi were – following their many appearances in the third season – intentionally excluded from appearing as regularly, thereafter. Between the airing of the third and fourth seasons, Brannon Braga declared, "At this particular instant, I never want to see another Xindi again. That's not to say they might not make a return. They're certainly a fun species to deal with. But at this point, I have to believe people will have had their fill." (Star Trek: Communicator issue 151, p. 35)