In the final episode, Nick along with his friends seeks to destroy Zerstörer, who plans on taking Diana and Kelly for his purposes.
The finale received a mostly positive reception from both critics and fans who praised the conclusion of the storylines and David Giuntoli's performance in the episode.
He warns Adalind (Claire Coffee) and Renard (Sasha Roiz) about it but they tell him that Zerstörer not only wants Diana (Hannah R. Loyd), he also wants Kelly.
Meanwhile, in the spice shop, Eve (Bitsie Tulloch), Monroe (Silas Weir Mitchell) and Rosalee (Bree Turner) do research to find a way to kill Zerstörer.
Diana appears and announces that Zerstörer will arrive as Nick's stick reveals his location, intending to retrieve it.
20 years later, in a modernized trailer, a person narrates how Nick managed to defeat him with his blood, and the ones from Kelly, Marie and Trubel, who is also revealed to be his third cousin on his mother's side.
He concludes by saying, "Some will say it's just a myth, legend or fairy tale but I know it's true because my father told me so", revealing to be a grown-up Kelly Burkhardt (Kevin Joy).
He is then joined by a grown-up Diana (Nicole Steinwedell), who grabs the Zerstörer's staff and tells him to get ready to hunt Wesen with their parents as well as Monroe's and Rosalee's triplets.
[6] The writers commented on the final season, "The fact that we got this concept going and we were able to actually explore all these psychological motivations dealing with history, mythology and fairy tales and dealing with religion and belief and all those things that you can't do on a regular show, and just have it come full circle, which you'll see in the end of the season, I think that's the most satisfying thing.
"[13] They also explained, "And Nick was ready to make that Devil's bargain, too, to have his loved ones back, until he had a somewhat supernatural experience of the strength of his blood and his ancestors who came before him, and then naturally who would come after him.
"[15] They also added that they were planning on bringing more previous cast members, among them Danny Bruno as Bud Wurstner but time constraints forced them to stop it from happening.
[16] About the time jump 20 years later, Greenwalt and Kouf stated that everyone is "all just one big, happy family, fighting evil monsters" with Trubel "definitely out there.
Terri Schwartz from IGN gave the episode a "great" 8.0 rating out of 10 and wrote in her verdict, "Grimm offered up a satisfying series finale that successfully brought the show to a close.
Nick's journey as a Grimm felt like it was given its proper due, and the episode both had stakes while also delivering a happy ending.
The jump forward in time at the end was particularly successful, promising that the fairy tale continues on even if we aren't watching it.
Club gave the episode an "A−" rating and wrote, "'The End' is a series finale that definitely has that mood of a last go-around to it, the feeling that there's nothing to be gained by holding back.
A literal devil walking the earth for ultimate power, a nigh nuclear poison to be brewed that takes all their combined talents, and the intervention of Grimms from beyond the grave — all of it is on display here.
Thankfully, that comfort isn't an empty promise, and Grimm closes its six-season run with a reminder that it's the people we love who give us our strength.
"[21] Kevin Yeoman from Screen Rant, wrote, "There's an It's A Wonderful Life quality to Grimm's final few moments (before an obligatory time jump reveals that Nick's son Kelly and Diana are carrying on the family tradition 20 years in the future) that brings everyone back to life, but robs the finale of some of its dramatic power.
But while wiping out nearly every character on the show would have been a memorably bleak way to end things, Grimm seeks to imbue the finale with emotional weight by applying the tried and true formula of the importance of family.
Whether or not that undercuts what was building up to be a remarkably violent and somber end will likely depend on how much mileage you get from the idea of ghosts returning to help the living in their time of need.
"[22] Kevin Yeoman from Oregon Live, wrote, "As 'Grimm' reminded us, before Walt Disney and other family friendly folk got their hands on the Brothers Grimm stories, they were often as dark as the Black Forest, with monsters preying on innocent victims, until the happy ending -- we hoped -- restored order.
The whole plotline with Zerstörer annoyed me from the outset, but as I noted in the review for Grimm Season 6 Episode 12, it was really the stupid choices made by normally-intelligent characters that galled me the most.
The site wrote, "'The End' is a fitting finish for NBC's fairytale series, and Giuntoli's performance is a crowning glory for his time on the show.