[SPOILERS for those not caught up on Supernatural ahead.]

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When a series has been on the air for as long as The CW's Supernatural, supporting characters tend to come and go, sometimes staying for only a handful of episodes, other times sticking around for a season or two. Some of the longest-tenured supporting players on Supernatural include Sam and Dean Winchester's surrogate father figure Bobby Singer (Jim Beaver), helpful angel Castiel (Misha Collins), and put-upon prophet Kevin Tran (Osric Chau).

Unfortunately, in the world of Supernatural, death is always a constant threat, albeit with the caveat that it isn't always the end of the line. In last week's season 12 finale, death more than made its presence known, with multiple important characters meeting their apparent demise. One of these casualties was Crowley (Mark Sheppard), who sacrificed his own life in an attempt to defeat Lucifer (Mark Pellegrino). Beginning as a hated adversary of the Winchesters, Crowley eventually became an uneasy ally, bailing them out of more than one deadly jam.

While many Supernatural fans might have assumed that Crowley would find a way to return from death and get back into the mix, it would now appear that the former King of Hell's reign might actually be over for good. Last night, Sheppard posted a goodbye message to the SPN fanbase on his Instagram, and TVLine has now confirmed that the actor won't be returning as a series regular for this fall's season 13. Check out Sheppard's post below.

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One thing that remains unclear is whether Crowley will appear at all going forward. After all, just because Sheppard is no longer a series regular, doesn't mean he can't ever return, as many deceased Supernatural characters have done before him. Based on the language in Sheppard's above post though, it would seem that he won't be appearing on the series anytime in the near future.

As popular as Crowley is with the Supernatural fanbase, it's arguably a good move for the show to actually have a big death stick for awhile, as many have criticized Supernatural's tendency to quickly undo emotional deaths over the years. Still, with no end in sight for Supernatural - at least according to The CW's executives - it's not hard to imagine Sheppard's devilish character popping up again in some form during a future season.

NEXT: Supernatural & Scooby-Doo Are Crossing Over in Season 13

Supernatural season 13 premieres this fall on The CW.

Sources: Mark Sheppard, TV Line