|Ship(s) captained or crewed|
- "You know what the chain of command is? It's the chain I go get and beat you with until you understand who's in ruttin' command here."
- ―Jayne Cobb
Background and personality
Jayne was a hired gun from Sycorax who did not fight on either side in the Unification War. He met up with former Independence fighters Malcolm Reynolds and Zoë Alleyne Washburne when his gang on Caliban tried to rob them. Noting Jayne's skill in tracking them, coupled with him learning how much Jayne was making with the current gang, Mal offered him a larger share of heists and his own bunk, and so Jayne shot one of his own companions and joined up with Mal instead, calmly asking, "How big a room?"
Jayne was good in a fight, and acted before he thought on many occasions. He was also somewhat thuggish and cruel; when arguing with Mal, he was not above insulting Mal's leadership skills by bringing up the events of the Battle of Serenity Valley, a highly sensitive subject for Mal. Although he often appeared to be somewhat stupid, he had his own peculiar wit. He had played successful jokes on the more intellectual Simon Tam (for instance, tricking Simon, who harbored an excessive fear of the vacuum of space, into putting on a spacesuit to board a pressurized ship). Jayne also had a keen sense of danger and was often the first to raise an accurate warning about impending peril.
Although often a strict mercenary, Jayne had his own code of honor. He was loyal to his employer as long as he was being paid well. When he had not acted up to his code of honor, he worked to atone for it, for instance by buying a crate of fresh apples and sharing it with the crew of the ship for what he did on Ariel. Jayne also demonstrated unexpected sentimentality when it was revealed that he sent some of the money earned by his mercenary activities home to his mother, Radiant Cobb. He also proudly sported a ridiculous orange knit cap with earflaps, simply because his mother made it for him.
Despite his occasionally harsh attitude, Jayne demonstrated that he truly did care about his fellow crew members; after Kaylee was accidentally shot by Lawrence Dobson, Jayne was naturally angered by this, but another side of this was shown when he was huddling by the window of the infirmary in bated breath to see if Kaylee survived the operation, and he went out of his way to help Mal close all air vents leading below deck to buy the former time to repair Serenity's engines when the life-support is down and even prepped a spacesuit for Mal for when he ran out of air without being told to do so (while Mal does appreciate this, he tells Jayne that he won't need it). Also, when Mal was about to space him as punishment for betraying Simon and River to the Alliance, Jayne told him with complete sincerity to lie to the other crew members about the reason for his death, caring about what they thought about him in the end; however, even before the Feds double-crossed him in order to take the reward money for themselves, he showed remorse for what he was about to do, especially after seeing Simon potentially risk the mission he arranged to save a man who had almost died due to his doctor's incompetence. After he discovered what the Alliance had done to River, he was willing to abandon the plan entirely.
Jayne kept a large arsenal in his bunk on Serenity. He had named his favorite and most powerful gun, a Callahan full-bore auto lock with customized trigger double cartridge thorough gauge, Vera. He acquired it after killing the previous owner, one of six assassins trying to kill him. After packing Vera into an oxygenated spacesuit so he could fire through outer space, Jayne preserved Serenity by disabling a carrion house (he also took care to kill the scrappers by shooting out their window, too). Jayne frequently carried a handgun based on a LeMat Percussion Revolver, and later carried a rifle named Lux.
Jayne doesn't have many acknowledged fears, but he has shown near-panic at anything to do with Reavers, a subpopulation of feral humans. He was convinced that fugitives Simon and his sister River Tam would bring the Alliance down on them, and this concern fueled his dislike of the Tams. He also had a notable fear of River, who slashed him in the chest once and unnerved him with her occasional outbursts, creating a rift that her generally sweet (albeit odd) nature did not help to heal. Jayne also demonstrated fear of dying in what he considered an unmanly manner, notably being "spaced."
Despite their seemingly opposite motivations, Jayne respected and liked Shepherd Book, and was carried beyond his self-interest and fear of Reavers by something the Shepherd "used to tell me,'If you can't do something smart, ... do something right'," to be the first to declare for Mal's suicidal plan to take the Alliance head-on. 
Jayne was regarded as something of a Robin Hood-like folk hero by the people of Canton on Higgins' Moon. They erected a statue of him in the center of the town and sung a song dedicated to "the hero of Canton, the man they call Jayne" ("The Ballad of Jayne Cobb") in which they tell how "he robbed from the rich and he gave to the poor." The true story was, however, less heroic. Jayne and his then-partner Stitch Hessian did indeed steal from Magistrate Higgins and drop the money on the town, but this was only because during his escape, Jayne's ship was attacked and damaged, and he needed to lose a lot of weight from the ship just to keep it flying. Jayne dumped the money in desperation, but only after having already thrown out his unfortunate partner. It was while visiting Canton that he let his emotional walls down the most, becoming deeply disturbed when the townspeople continued to idolize him after learning the truth. He tried to deal with this, even going to Mal for help in doing so.
Behind the scenes
Jayne's very favorite gun, Vera, is possibly named for the actress Jayne Mansfield whose birth name is Vera Jayne Palmer.
Adam Baldwin also voices a character in Halo 3: ODST, Corporal Taylor H. Miles, that has obvious similarities to Jayne—one of his lines references a gun called Vera, another to the grenades he left behind in Serenity, and he serves under Nathan Fillion's character, GySgt Edward Buck.
Adam Baldwin also alludes to his character in his other show, Chuck. His character, John Casey, on one occasion refers to his car as 'shiny' in the context the word is used in Firefly. He also comments about an intelligent kid in another episode, "What's he gonna do? Hurt me with his brain?" (referencing the scene in "Trash" when River casually tells Jayne, "Also, I can kill you with my brain.") Another time he says Chuck is "damaging [his] calm", referencing Jayne's remark toward River in Serenity.
- Firefly – "Serenity" (First appearance)
- Firefly – "The Train Job"
- Firefly – "Bushwhacked"
- Firefly – "Shindig"
- Firefly – "Safe"
- Firefly – "Our Mrs. Reynolds"
- Firefly – "Jaynestown"
- Firefly – "Out of Gas"
- Firefly – "Ariel"
- Firefly – "War Stories"
- Firefly – "Trash"
- Firefly – "The Message"
- Firefly – "Heart of Gold"
- Firefly – "Objects in Space"
- Better Days
- Those Left Behind
- The Other Half
- The Shepherd's Tale (Appears in flashback(s))
- Serenity movie
- Serenity novel
- The Magnificent Nine