The Winchester brothers have faced a lot of evil creatures in Supernatural, but over the years their most powerful enemies — demons — have faded farther and farther into obscurity. With each new season, the role of demons in the apocalypse has lessened and demonic characters have worsened. Having started as true threats in season 1, demons slowly changed into occasional allies and then became relics of the past, as Sam (Jared Padalecki) and Dean Winchester (Jensen Ackles) battled ever more powerful forces.

Supernatural began in 2005 with a simple premise: two brothers hit the road to find their missing father, and along the way battle supernatural monsters like vampires and ghosts. The first major plot arc, in which the brothers defeat archangels Michael and Lucifer (Mark Pellegrino) to prevent the apocalypse, concluded in season 5, prompting the departure of showrunner Eric Kripke. In subsequent seasons the brothers fought against angels, Leviathans and even God himself (Rob Benedict), and Supernatural is now set to conclude its 15th and final season on November 19.

Related: Supernatural: Why John Winchester Doesn't Need To Return For The Finale

Demons played a huge role in the early seasons of Supernatural, starting in the pilot episode. The initial hook for audiences came with the death of the Winchesters' mother Mary (Samantha Smith) and identical demise of Sam's girlfriend Jessica (Adrianne Palicki) 22 years later, which the brothers later discover is the work of demons. In seasons 1 and 2, the demon Azazel (Fredric Lehne) is set up as the Big Bad. Demons continuef to make frequent appearances in seasons 3, 4 and 5 as followers of Lucifer. As the show progressed, however, demons became more run of the mill threats. Now, they've been entirely abandoned in favor of more powerful enemies.

Not Your Typical Monster Of The Week (Seasons 1-2)

Azazel flashes his yellow eyes

In the early days of Supernatural, demons were few and far between. With Azazel a.k.a. "Yellow Eyes" as the main villain of seasons 1 and 2, the nature of demons had to remain a mystery, and that ambiguity only increased their fear factor. As the boys faced off against shapeshifters and other monsters each week, supernatural creatures became familiar. Demons were held in reserve as something worse.

After being introduced onscreen in season 1, episode 4, "Phantom Traveler," demons often appeared only in pivotal episodes that tied into the overarching story. When they did show up, their ability to appear human through possession made them more of a threat than anything the Winchesters had faced so far. Mimicking humans gave demons the power to trick the Winchesters into thinking they were friends or family. With their defenses lowered, the brothers were easier to manipulate and attack.

One of the most prominent demons in the early seasons was Meg (Nicki Aycox), who befriended and tricked the Winchesters. Meg's true loyalties are revealed relatively quickly, but she continues to use her human body to target hunters. In season 2, Meg even possesses Sam himself, committing acts of violence while he's helpless to stop it - a truly frightening prospect. Azazel also uses his ability to possess humans, specifically John Winchester (Jeffrey Dean Morgan), to try and trick Dean into handing over the Colt, a powerful weapon against demonkind. As proven in the Supernatural season 1 finale, possession has the added benefit of keeping the host alive, giving demons a human shield and last-ditch escape plan if they're discovered.

Related: Supernatural: How Old Sam & Dean Winchester Are In The First and Last Seasons

Another frightening aspect of demonkind is revealed in season 2 with the introduction of the crossroads demon. As the Winchesters eventually discover, making a deal with the devil is tempting, but always has consequences. When John sacrifices himself to save Dean, and Dean sacrifices himself to save Sam, crossroads deals are used as a way to show how humanity can be its own worst enemy.

True Believers (Seasons 3-4)

By seasons 3 and 4 of Supernatural, the Winchesters are more familiar with demons, having even gotten anti-possession tattoos (shown for the first time in season 3, episode 12, "Jus in Bello"). But demon activity is at an all time high, with hundreds having been released through a door to Hell. Unlike some other monsters who follow their animal instincts, demons are intelligent and somewhat organized. Many of the demons who appear in seasons 3 and 4 are followers of Lucifer, including Ruby, a double agent who engaged in a months-long undercover operation to help free Lucifer from Hell.

Ruby's true nature is revealed in a shocking twist in the season 4 finale, which shows just how insidious demons can be. Her character was particularly effective because she had Sam Winchester (and the audience) convinced she was on the side of the light, even as she was drawing Sam deeper and deeper into the darkness. Ruby's character brought out a true fear in people that they may have done something bad in the name of good. The way demons exploit the sins and weaknesses of humanity in season 3 and 4 is much more terrifying than a straightforward physical attack by a vampire could ever be. Demons reached peak form in season 4, embodied by Ruby, who exploited Sam's emotional weaknesses to create distrust, fear and hostility between the Winchester brothers.

A Deal With The Devil (Seasons 5-7)

Crowley smirking holding the Colt

The role of demons as antagonists in Supernatural began to shrink in season 5, with many of their abilities having already been explored. Like the Winchesters, the audience had already been frightened and tricked by demons and were starting to become familiar with the creatures. Angels, who were still mysterious and unknown, stepped into the spotlight. The antagonists in mid-series Supernatural are creatures more powerful than demons, such as Leviathans.

Related: Supernatural: Chuck's God Powers (& Weaknesses) Explained

Subsequently, the Supernatural writers changed their position on demons, transforming them from direct antagonists into untrustworthy allies with the introduction of Crowley (Mark Sheppard). The characteristics that made demons so disturbing in season 1-4 begin to disappear in season 5. Instead of manipulating the Winchesters, Crowley makes a deal with them. Instead of tearing the Winchesters apart, Crowley supports them (kind of). Instead of encouraging destruction, Crowley embraces a philosophy of survival, becoming the ultimate businessman.

The spark of humor and levity Crowley shows as a demon is refreshing, but not that scary. Supernatural attempted to revive the deceptive nature of demons in seasons 6 and 7, with Crowley playing his own game, but his pursuit of worldly goals is simply not as compelling as a plan to destroy the world.

The Hierarchy of Hell (Seasons 8-10)

Dean with the First Blade In Supernatural Season 9

Demons experienced a brief resurgence in seasons 8 and 9 of Supernatural when Abaddon (Alaina Huffman), the last Knight of Hell, took her place as Big Bad. By season 8, the Winchesters were truly experts at fighting demons and equipped with reliable weapons (the demon knife and the Colt). Abaddon, a super-powered demon immune to the knife and to exorcisms, presented a new challenge. Abaddon also opened the door to an exploration of Hell's hierarchy, leaving room for more Knights - namely Cain (Timothy Omundson) - to appear. The demoness presents a compelling character with power and style, combining the best of both worlds.

At the same time, the line between humans and demons becomes more blurred when Dean takes on the Mark of Cain and begins displaying demonic characteristics — rage, impatience and a lack of impulse control. Dean's transformation into a demon at the end of season 9 is one of the most notorious cliffhangers in the series, and his subsequent struggle with his own sins brings back one of the most effective qualities of demons: their ability to reflect the evil of humanity. Dean's demon storyline echoes early-season themes of an internal struggle between good and evil. After season 10, though, it's all downhill for residents of Hell.

Related: Lucifer Is Becoming Supernatural's New Crowley

Working Together At Last (Seasons 11-12)

When Amara (Emily Swallow) a.k.a. the Darkness is unleashed in season 11 of Supernatural, demons begin to fade into obscurity. The power and destructive instincts of demons simply pale in comparison to a cosmic force from the beginning of time. As the Winchesters and Castiel (Misha Collins) are once again faced with an overwhelming threat, their relationship with Crowley becomes trusting and amicable. That relationship is on full display in season 12, episode 3, "The Foundry," when Crowley and Castiel work together to track down Lucifer.

A speck of respect remains for demons in the show's exploration of the four Princes of Hell, but battles with the Princes are few and far-between and almost always one-offs. Even the most suspenseful, heart-pounding fight with a demon in seasons 11 and 12 — the battle with Ramiel in season 12, episode 12, "Stuck in the Middle (With You)" — is completed within the hour. The episode is mostly gripping because it reminds audiences how quickly a straightforward hunt can turn bad. Another Prince of Hell, Dagon (Ali Ahn), presents little threat to the Winchesters.

Crowley's death in the season 12 finale is representative of the larger death of demons in Supernatural's canon. His loss is also the loss of the last compelling demonic character in the series. In some ways, it's a mercy killing — Crowley and other demonic characters often played the role of comedic relief in later seasons, and no longer had any major role in the events of the plot.

The Fall Of An Empire (Seasons 13-15)

10 Rules The Angels In Supernatural Have To Follow

Demons are all but forgotten in season 13, 14 and 15 of Supernatural. The last remaining Prince of Hell, Asmodeus (Jeffrey Vincent Parise), is one of the most underused characters in the series, often drawn on merely to fill holes in the plot or present a minor roadblock to the Winchesters. Squabbles over leadership once again erupt in Hell, but with ongoing battles between archangels, God and Amara, who cares about what's going on down under? Luckily for Supernatural fans, there's always a new character to explore — in this case, the nephilim Jack (Alexander Calvert).

More: Supernatural: Predicting How The Winchesters' Story Ends