Developed, produced, and co-written by Jason Katims, the series debuted on October 6, 1999 on the WB, and later shifted to UPN for the third season.

Roswell High was originally developed by 20th Century Fox Television and Regency Television for the Fox Network, but it eventually landed on The WB (retitled simply to Roswell) thanks to the latter network's offer to extend a full 22-episode upfront commitment.

[4] The series premiered on October 6, 1999, on The WB in the United States to generally favorable reviews,[5][6] and quickly gained an outspoken fanbase.

Starting with the second season, after a fierce fan-driven campaign involving bottles of Tabasco sauce—a favorite condiment of the show's alien characters—were sent to the network's offices, veteran science fiction writer Ronald D. Moore was brought in as an executive producer and showrunner to further develop the science fiction elements of the show.

At the beginning of the pilot episode, Liz is waitressing in her parents' restaurant when a disagreement between two customers breaks out.

We are introduced to a character named Max Evans (Jason Behr), a seemingly normal high school student, who rushes to Liz's aid and saves her life by healing the gunshot wound with his alien abilities.

To hide what he has done, Max pours ketchup on Liz before fleeing the scene with his friend Michael Guerin (Brendan Fehr).

When she confronts him, Max admits that he, his sister Isabel (Katherine Heigl) and their friend Michael, are aliens from the planet Antar, whose spaceship crashed at Roswell in 1947.

As the show's first season conculdes, it is revealed that Max, Isabel, Michael and Tess are clones of the "Royal Four" of Antar, the planet these characters come from.

Their mission is to one day return to Antar and reclaim the throne from Kivar, Max's enemy in his previous life.

Along with renegade Skin Courtney (Sara Downing), a Crashdown Café waitress, who believes Michael, not Max, should have been in charge of Antar, the group travels to Congresswoman Whitaker's home town to discover it is inhabited entirely by Skins who are ready for the "Harvest".

In order to survive Earth's climate they create husks (fake bodies) which last around 50 years.

These clones have killed their Max/Zan and come to Roswell to convince Max to join them at a summit meeting of the families of the five warring planets.

Nicholas returns as a voice for Kivar, and it is revealed the owner of the UFO museum, Brody Davis (Desmond Askew), was used by an alien many times to communicate on Earth, acting as a puppet, explaining why he believes he was abducted by aliens although he has no memories of the incident.

Max and Tess go with Isabel and Michael's clones to New York, where they are told they can return to their home planet if they give Kivar the Granilith (the rock which came with the Royal Four when they landed on Earth), but remembering advice from Liz, Max turns down Kivar's deal.

When Alex returns from a trip to Sweden, he finally makes a romantic connection but he dies tragically in a car accident.

Liz is suspicious of the police ruling Alex's death a suicide and conducts her own investigation, uncovering evidence he may have been murdered.

Liz discovers that Tess is the villain, having brainwashed Alex to translate the Destiny book and is responsible for his death.

After being cancelled by The WB, Roswell returned for a third season on UPN with a storyline around Max's quest to save his son which doesn't get off to a good start when he and Liz are arrested in Utah after holding up a convenience store.

As the season unfolds, their father is diving deeper into the past of his children, not happy with Max's criminal behaviour.

Kivar tries to compel Isabel/Vilandra to travel through a portal back to their home world, while Max and Michael attempt to stop them.

Michael unknowingly inherited Max's powers after his death, and then he heals Isabel during an emotional moment.

Seeing Liz is about to die, Max takes control over the body and uses his powers to save her life while he hits the ground.

Meanwhile, the FBI has been studying the group for many months and is closing in on them, and after Liz also displays alien powers inherited from Max, including premonitions, she also becomes their target.

Max, realizing his son can have a normal life, gives him up for adoption; showing the Evans' parents driving the child away to New York.

The series closes with Liz getting a premonition of her, Max, Michael, and Isabel dying in an FBI setup, so they decide to leave Roswell after their high school graduation.

In 2002, Simon Spotlight Entertainment picked up the Roswell range and published eight more novels.