Over fifteen seasons, long-term story of the Winchester brothers and who were oftentimes introduced spectacularly.
Whether they get their own scene and some epic music to prepare the audience for the character's next appearance or simply have the character burst onto the scene in a jaw-dropping manner, the Supernatural crew created a lot of memorable debuts for a lot of equally as memorable characters.
Charlie Bradbury
Some fantastic introductions do not make the cut here, such as Rowena, but what gives fellow red-head Charlie Bradbury her spot is how fitting her introduction was.
Like Charlie, the entrance was not exactly for everyone; it was not this epic arrival; it was simply this lovely, nerdy girl rocking a Princess Leia t-shirt blasting "Walking On Sunshine" through her headphones as she dances her way into work. It was a fitting introduction to one of the show's best female characters.
Raphael
Raphael is an incredibly powerful being, one of the four main-world Archangels, and the third created by God, but even alongside Michael and Lucifer is one of the most unlikable angels.
His introduction, though is incredibly badass. He actually has two, in season four, he does not appear in a vessel, but he arrives to protect Chuck from Lilith. His actual introduction into his vessel comes in season 5 when he possesses his vessel to confront Cas and Dean, shorting out the electricity across the entire Eastern Seaboard and putting Dean in his place.
[Alternate] Michael
From one Archangel to another, Michael from the other world made much more of an instantaneous badass entrance than regular Michael did back in the Kripke-era.
Arriving to greet the odd pairing of Lucifer and Mary Winchester, Michael hits the ground like a meteor, and in the dust, fans see the silhouette of angel wings. It is an epic image, and even if the character got less cool over time, he immediately grabs the audience's attention.
Jack
Jack Kline is one of the most refreshing inclusions to the final few Supernatural seasons, becoming not only a fourth member of Team Free Will but also becoming the most powerful being in the universe, crucial in defeating God.
His entrance was wild. So much was going on between traveling between the two worlds, Cas dying, Crowley sacrificing himself, Lucifer being Lucifer, and him emerging yellow-eyed as a fully grown adult rather than the baby he was. It was pretty awesome all around, if not disorienting, especially considering nobody knew if would be good like Castiel and Kelly or evil like Lucifer.
Lucifer
Speaking of Lucifer, he is a character who was only intended to appear in one season of the show per the idea of the original five-season arc, yet who continued to impact the show right up until its final season.
Back in season 4, Lucifer made his introduction, although not in his vessel form. Putting his "Lucifer Rising" appearance here may be a bit of a cheat considering Raphael's entry relating to his vessel introduction. But, that moment when the cage opens and a blinding light hits Sam and Dean as they process everything that went down with Lilith, Ruby, Sam, and the 66 seals is special and genuinely quite frightening. Sam's "Dean, he's coming." is the icing on the cake as the audiences see the boys genuinely afraid for what is to come.
Crowley
When it comes to bad guys, there are few if any characters better than Crowley; even if he did turn good, the character is still one of Supernatural's best, and his introduction was so fitting.
Fans first meet him in the middle of a demon deal, an important one considering he was King of the Crossroads at the time. He banters with this old businessman, kisses him, and instantly makes himself a presence on the show. It is arguably an underrated introduction compared to those with more pomp and circumstance.
Dean Winchester
Way back in 2005, the Supernatural journey started with two babyfaced versions of the dedicated fandom's favorite pair. Ignoring the child versions of the characters from the opening moments, fans get introduced to Dean specifically in a great way.
Audiences meet an adult Sam moments earlier in a bar on Halloween at college, in a pretty standard character intro. Dean, though, breaks into Sam and Jess' house, starts a fight with Sam, and the brother banter begins. This scene births some iconic lines from the show, including the "Dean." "Hey, Sammy." exchange and "Dad's on a hunting trip, and he hasn't been home in a few days."
Lilith
The main villains of Supernatural got progressively meaner and more powerful in the Kripke-era, going from Prince of Hell Azazel to the first demon Lilith, all the way to Lucifer.
Lilith's debut comes in one of the very best episodes of Supernatural's early years "Jus In Bello," after fending off hordes of demons in a small town jail with Agent Henriksen and station staff, Lilith arrives in the Winchester's wake, destroying the police station and all those inside with a blinding white light. All while in the vessel of a little girl.
Death
As great as all the above introductions are, every Supernatural fan knows there are only two contenders for best character introduction, one of which is Death.
Getting his own isolated scene away from the Winchester's, Death arrives in Chicago in his famous pale steed, serenaded by the wonderfully eerie "O' Death" and walks in slow motion on the sidewalk, with perhaps the peak of the scene being the moment he brushes his shoulder, instantly killing a rude erby. It is both bone-chilling and epic.
Castiel
The other of the two character introductions? Castiel, of course. His character introduction in "Lazarus Rising" is as iconic and well-ed amongst fans as it is beautifully crafted and epic to watch.
With Bobby and Dean waiting in anticipation for who or what got Dean out of Hell, Castiel arrives and instantly proves himself to be a power beyond anything they have encountered to that point. Castiel shorting out the lights, the brilliant shot of his angel wings (the first seen in Supernatural), Misha Collins' performance, and the overall presence of the character, all this builds up to make this introduction so wonderful. Add in his meeting Dean for the first time, beginning the journey the two will share over the next dozen seasons, and more iconic quotes like "I'm the one who gripped you tight and raised you from perdition" and it is really no contest.