Characters like Bobby, Castiel, and Crowley may have gotten more screen time than these ladies of Supernatural, but that doesn't stop any of them from impacting the story in huge ways, whether it's helping the main characters out of near-death situations or kickstarting an entire season's plot!
The series may be about the Winchester brothers, but supporting characters play a huge role in the happenings of the show, which currently sports a total episode tally of 315. These counts are the total number of episodes in which each character is featured, including in time travel situations, dreams, ghosts, and flashbacks that haven't been seen before. They do not include flashbacks of scenes that have already been featured, alternate universe versions of the characters, episodes where female characters are depicted by men, and episodes with no on-screen appearance.
Claire: 7 Episodes
This heading isn't entirely accurate. Claire shares the #10 slot with Charlie Bradbury and Jo Harvelle, each of whom has also been featured in seven episodes, but Claire is the only of these characters who are still alive — the original version of her, that is — and has the most potential to have a continued role on the show.
Claire is the daughter of Jimmy Novak, Castiel's vessel. She returns to his and the Winchesters' lives in season 10, and she ends up staying with Jody Mills, a hunter and sheriff based in Sioux Falls, where she practices her hunting skills and even saves Sam and Dean from the Bad Place.
Abaddon: 9 Episodes
Abaddon causes some massive trouble when she travels into Sam and Dean's time. It's her role in the show that introduces the boys to the Men of Letters bunker, which they still call home. She is also the reason that Dean takes on the Mark of Cain, which causes a row of dominoes — Dean becoming a demon, the Darkness emerging, Mary returning — to tumble down after it, all starting with her entrance to their world.
Ellen: 9 Episodes
When Ellen and her daughter, Jo, are introduced in season two, we see the first female hunters in action on the show. Ellen gives the boys a few cases and offers them advice on occasion, and her bar, the Roadhouse, becomes a sort of hub for them.
She and Jo are part of the team that tries to kill the devil in season 5's "Abandon All Hope." Although they both die in this episode, Ellen returns in "My Heart Will Go On," where it is revealed that they both survived in an alternate reality where the Titanic never sank.
Billie: 10 Episodes
Although Billie was only introduced a few years ago in season eleven, she has impacted the show in ways not many characters could. She puts a unique spin on the villain-turned-ally type of character in that... well, she could still go either way. As a Reaper, she made it clear that the rules were the rules and what dies needs to stay dead. As Death, she continues to abide by the rules of the universe, so there's really no telling if or when she will take the boys for good.
She has, however, helped them along the way, giving them a door to Hell to see Lucifer, souls from the Veil for the bomb that would defeat Amara, and assistance from Reapers in their fights against Rowena and Michael.
Lisa: 11 Episodes
She may not have had a huge role in the show, but she has more episodes under her belt than most of the female characters. Lisa was a big part of Dean's story for a large portion of the series. Introduced in season three as his former "bendy weekend," she becomes the embodiment of the normal, civil life he dreams about. After Sam jumps into Hell in season five, Lisa takes Dean in, and the two, along with her son, Ben, make a home for themselves with each other.
Meg: 11 Episodes
Meg started as the season 1 villain and ended up a beloved, complex character. Fans raged over her season 8 death after everything that she had been through and all she had done for the Winchesters. She looks after Castiel when he falls into a coma and calls Sam and Dean when he wakes up, then helps them battle the Leviathans.
She also helps them fight Crowley. Without her, they would never have beaten him to uncovering the angel tablet in "Goodbye Stranger." They may have had a touch-and-go relationship, but the Winchester narrative may have been completely different without the addition of Meg.
Jody: 16 Episodes
Of every female character in the show, Jody has had the longest run to date, having appeared in every season since her introduction in season five. She is usually only featured in one or two episodes per season, but it's still quite an accomplishment in a show with all-male leads and an ever-revolving cast of supporting characters.
Her contribution to the show even led to the backdoor pilot of a heavily supported spin-off, "Wayward Sisters," which was to revolve around her and her adopted daughters. Although the spin-off never panned out, she was featured in an episode the next season, and fans hope to see her in the show's final season as well.
Ruby: 16 Episodes
Although she only starred in two seasons and was hardly mentioned after her death over 10 years ago, Ruby continues to have an effect on the show's story. She takes on a strong role in the Winchesters' story as soon as she bursts into the room and saves Sam from a demon attack.
Without her plot to trick Sam into opening the cage to Hell and guiding him through his demon blood addiction, the brothers might be dealing with an entirely different set of problems.
Rowena: 31 Episodes
It's no secret that the Winchester brothers have died several times, but those numbers would be a lot higher if Rowena hadn't been around to save them. In fact, she plays a huge part in saving the world more than once, taking down Amara and Lucifer and opening the portal to the Apocalypse World.
Without Rowena, there's no telling where the main characters of the show would be, or if there would even still be a show to talk about. Even her death in season fifteen will continue to have a lasting effect on the show and its direction.
Mary: 37 Episodes
It was Mary's death that started the plot of the entire show, so it seems fitting that she would have the biggest role. Even if she wasn't around for most of the series, her story after she is resurrected by Amara is a major part of season twelve.
It's also when she faces off against Lucifer and winds up trapped in an alternate universe that Sam and Dean are prompted to gain access to the Apocalypse World, a world which was a direct result of Mary never having made the demon deal to save John.