Supernatural has once again contradicted fan opinion with regards to Castiel's nickname. First introduced in the season 4 premiere, Castiel was sent from heaven to aid the Winchesters but soon became their adopted third brother (sorry Adam), frequently rebelling against his angelic brethren in favor of Sam and Dean. As the trio became better acquainted with each other, the full "Castiel" name was eventually dropped in order to match the Winchesters' single-syllable monikers, but fans have long been divided over whether the angel's nickname is "Cas" or "Cass."

Logically speaking, "Cas" might be the immediate answer, since the full name itself only has a single "S" in its spelling, however, Supernatural has frequently suggested otherwise. Promotional material and official subtitles both opt for the "Cass" option, while the actor responsible for playing the character, Misha Collins, revealed on Twitter that scripts also use that spelling. Supernatural creator, Eric Kripke, has confirmed that he prefers "Cass" both because it looks nicer, and to ensure the correct pronunciation. More recently, evidence has been mounting on-screen, as well as from behind the scenes. Metatron is seen writing "Cass" when referring to his fellow angel, and a season 12 phone screen shot showed the same. Despite the collated evidence to the contrary, many fans still insist that "Cas" is the correct spelling.

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In its final season, Supernatural has been on somewhat of a fan-pleasing farewell tour, reintroducing old characters and tying up loose ends from the show's history. If there was ever a time for Supernatural to change their minds and accept the fans' way of writing Castiel's nickname, season 15 offers the final opportunity to do so. Instead, the writers have doubled down on the double-S nickname, proving once and for all that "Cass" is the way to go. In the final season's "Last Call," Dean is forced to hand over his cellphone at a bar, leaving Castiel high and dry when the angel tries to call about Sam getting hurt. As the camera lingers on the glowing phone screen, Supernatural once again confirms that, as far as the Winchesters are concerned, their heavenly friend is called "Cass."

Castiel looks concerned in Supernatural

This instance will almost certainly be the last time Supernatural references the Cas vs. Cass debate on screen, acting as the show's final word on the issue. Although the widely used alternative might make more logical sense, it's hard to disagree with both Supernatural's creator and multiple examples of the right spelling on-screen. Admittedly, there are few corresponding examples of this hypocorism in the English language, but perhaps the nickname makes more sense in Enochian. In either case, as much as many fans may not be happy with the decision, Cass is now confirmed as canon, if it wasn't set in stone already.

Time will tell whether the end of Supernatural forces fans to finally embrace the double-S spelling, or whether the single-S supporters will continue to defend their viewpoint even as Sam and Dean bow out after over a decade in the monster hunting game. From Supernatural's point of view, at least, there's no more information they can offer to settle the argument. The final season has spoken, adding to previously standing evidence, and if Dean Winchester's phone says it, surely it must be true.

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Supernatural season 15 continues with "Our Father, Who Aren't In Heaven" December 12th on The CW.