Serenity is a line of comic books published by Dark Horse Comics from 2005 to 2017. It is a canonical continuation of Joss Whedon's Firefly television series and the 2005 film Serenity, which are all part of the Firefly media franchise. It was not an ongoing series; rather, it consisted of a number of miniseries and one-shots, released sporadically.

Starting in 2018, Boom! Studios began publishing its own line of Firefly comics.

Initially, Joss Whedon invited Brett Matthews to co-write a story to bridge the series and the film. Matthews had previously worked as Whedon's assistant on several Buffy, Angel, and Firefly episodes, and had written the script for Firefly episode "Heart of Gold". According to Matthews, Those Left Behind was originally an anime project, which fell through, leading to the story being released in comicbook form.

Serenity: Those Left Behind is a three-issue miniseries, created in 2005 as a tie-in to the film Serenity. The series was written by Joss Whedon and Brett Matthews, illustrated by Will Conrad, lettered by Michael Heisler, and colored by Laura Martin.

Those Left Behind is set after the events of the Firefly television series, to function as a bridge leading into the Serenity film. It shows Inara's departure from Serenity's crew, establishes Shepherd Book's intention to leave the ship, introduces several characters important to the film's storyline, including the Operative and Mingo and Fanty, and resolves the Hands of Blue plotline from the television series. Those Left Behind also reintroduces Lawrence Dobson, an Alliance agent who was (apparently) killed by Mal in the Firefly pilot episode. Whedon had always planned to bring back Dobson, but did not have the opportunity before the series was cancelled.

The second three-issue miniseries, Serenity: Better Days, was announced by Dirk Wood of Dark Horse Comics during WonderCon 2006. The three issues were released in March, April, and May 2008. Whedon, Matthews, Conrad, and Heisler returned, but colourist Laura Martin was replaced by Michelle Madsen. Adam Hughes served as cover artist, creating three covers, each depicting three of the nine Serenity crew members, which together form a triptych. Jo Chen drew the 2008 trade paperback collection cover.

Better Days is set between the television series and the film, but before the events of Those Left Behind, in order to have all the core characters aboard the Serenity, and to better capture the "heart and status quo—in as much as there even is one—of the [television] series." The comic sees the crew of Serenity pulling off a successful job, which results in unexpected wealth and complications.

The three issues were collected as a trade paperback in October 2008. This work won Diamond's 2008 Gem Award for "Licensed Trade Paperback of the Year". In 2009 Better Days was one of six nominees for the inaugural Hugo Award for Best Graphic Story. The miniseries came second to Girl Genius, Volume 8: Agatha Heterodyne and the Chapel of Bones.