A TV series has a few advantages over a stand-alone film when it comes to characters and storytelling. It can explain lore, characters, and locations across multiple episodes when a movie doesn't have time to go into that much depth. This means fans can enjoy a more diverse and immersive universe of heroes and villains. Writers often find inspiration in existing legends and stories to widen the scope of the cast. There's a trend of serialized shows on various home streaming services that focus on folklore and myths about demons, vampires, witches, and other magical beings.
Supernatural would have to include a whole array of interesting villains, given the otherworldly nature of the show and how long it's been running. A few are original creations but most are borrowed from existing Biblical texts and other ancient stories of the ongoing battle between the forces of Heaven and Hell. For viewers that are curious about how that aligns with their own zodiac sign, there's a Supernatural villain that can fill that role.
Aquarius - Lilith
Lilith was the first demon, and perhaps the most powerful, since the storyline never revealed if it was even possible to destroy her. She died of her own free will to break Lucifer out of his prison, a surprisingly humanitarian act for a demon. Not surprising, however, if that demon is an Aquarius. This is the sign with the capacity for using their power to restore balance and does so without regard for limitations, including sacrificing their own existence.
Pisces - Cain
The dark side of the Pisces sign can turn to martyr-hood, doomed to be a perpetual victim in their own story. That could also be a quick summation of Cain's legacy, destined to be known as one of history's greatest monsters when the true story is much more nuanced. The character of Cain also functions as a theme-character in the show, wavering between good and evil, and Pisces is the sign that tends to have all the answers.
Aries - Alternate Michael
In Supernatural, there are two incarnations of the Archangel Michael. This is the Michael that existed in the Apocolypse World and possessed both Dean Winchester and the witch Rowan MacLeod as a malevolent force.
The sign of Aries is about beginnings and endings, specifically of the destructive and turbulent kind, which aligns them with Michael. Aries is also a highly analytical and intellectual sign, and the audience watches Michael as he eventually rationalizes that humanity is too sick to survive.
Taurus - Dick Roman
A Taurus is the kind of person who makes a plan and sticks with it, even if things don't go exactly as they intended. They also tend to have an everyman persona that hides their real power, a tactic that allows them to go unnoticed, unlike other flashy signs that thrive on attention. The secret leader of the Leviathans, Dick Durban, is very much a Taurus. He hides and bides his time, stubborn and uncompromising, refusing to work with demons even when an alliance would be beneficial.
Gemini - Abbadon
The dual nature of human and demon is one of the most obvious similarities between Abbadon and a Gemini person. There's also the detail in the storyline where she was originally Lucifer's jailor but then changed her mind to be one of his supporters. It could not have been easy to balance the life of a human with the career of a demon, but the intelligent and adaptable Gemini could do it.
Cancer - Eve
Her nickname is the Mother of All, and Cancer is a sign that's all about motherhood but that doesn't just mean having babies, it's about creation. Eve didn't just create several new races, she existed even before the angels did, and claims to have a direct connection with some of the oldest and most powerful beings in existence.
Her beginnings are lost in the mists of time, and other than the fact that she's related to the Leviathans, where she came from originally is virtually unknown. If there's any sign that claims to have known God personally, it would have to be the ancient and understanding Cancer.
Leo - Lucifer
Lucifer is the character that likes to be watched, so immediately he and Leo have this one fundamental trait in common. Lucifer likes to be treated like the very important person that he is and be surrounded by admirers. He possesses natural leadership qualities along with the flair and charisma to make sure all eyes are on him as often as possible, the perfect metaphor for a person born under the Leo sign.
Virgo - The Maker
Not all of the vampires that appeared on Supernatural were villains, and several were either neutral, flipped between sides, or openly helped the Winchesters. The Maker, however, was one that was pure evil. Also known as the Old Man because of his very advanced age, he usually took on the form of a young man barely past his teenage years. Careful and methodical like the Virgo person, The Maker has not only been able to survive for hundreds of years but has created many other vampires.
Libra - Azazel
Azazel is one of the evilest, destructive, and most malicious beings to ever exist, and despite his awesome power, he's able to act as both a leader and a loyal minion. A Libra would also strike a similar balance in their personal and professional life, favoring a diplomatic conquest over a violent one.
Azazel was always a loyal minion of Lucifer, and it's typical of those born under the sign of Libra to form a dedicated partnership with a complimentary friend or partner. Even death can't seem to erase the influence of a Libra, and Azazel continued to haunt the Winchesters in nightmares and hallucinations years after he was defeated.
Scorpio - The Darkness
It's the Scorpio sign that understands the rules of the universe better than other signs, which is why they would see themselves in The Darkness. Also known by her other name, Amara, she's apparently God's sister and the only entity just as old and powerful as he is. Passionate and stubborn, The Darkness wanted humans to live in her own version of a blissful paradise, but on the other hand, she wanted to destroy God's creation to make her brother suffer.
Sagittarius - Rowena MacLeod
There's some debate as to whether or not Rowena is a true villain and that's one of the reasons she's likely a Sagitarrius. Freedom is more important to the Sagistarrius person than almost anything else, which would explain why Rowena changed sides and loyalties so many times throughout the course of the series. This is a sign that likes changes and travels in search of knowledge and meaning, very much like one of the greatest and most powerful witches in the Supernatural franchise.
Capricorn - Metatron
It's not just the parallel of the cranky old man, which seems to be Metatron's incarnation no matter who's playing this iconic mythological character. As the scribe of God, he's a symbol of time and responsibility, two concepts that define the Capricorn. He starts out as an affiliate of God and good, taking the side of the Winchesters, but a thirst for revenge turns him into a force for evil. It's also typical of a Capricorn to turn on something they once loved, which is exactly what Metatron does.