There's a word that fits, but only if I amend your request a little.
Götterdämmerung is "the last in Richard Wagner's cycle of four operas titled Der Ring des Nibelungen" and means "the twilight of the gods." (Wikipedia). (Metaphorically speaking, the end of an epoch.)
It has come to mean "A turbulent ending of a regime or an institution." (The Free Dictionary).
The amendment is a slight reordering of "The end of a distinctive period in the history of someone or something" to "The distinctive end in the history of someone or something."
Of course, götterdämmerung only works if something ends with a bang, rather than a whimper. I rather like sunset if it ends quietly.
Author Margaret Mitchell has heroine Scarlett stumble over some German word in Gone with the Wind. (Rhett expresses surprise that Scarlett has even heard of the word.) And the article The American Gotterdammerung begins with
Throughout the book “Gone with the Wind” there is a recurring theme of the Gotterdammerung, a winnowing out of the weak and the strong coming through.
A handful will give you points for a literary reference, but unfortunately, many will think you're uttering a profanity.