to this day in 1964 when Soraya Esfandiary Bakhtiari, former queen consort of Iran, wore this fantastical costume headpiece in a scene from the Italian film, I Tre Voti (The Three Faces), in which she starred. It’s a whopper.
Photo from Getty as indicated
Royal Hats 
Amazingly she still looks gorgeous and even elegant with all that on her head! I never knew Soraya starred in a film and I remember reading a book about her when I was growing up. I do remember that she was very sick on her wedding day to the Shah and again still looks fabulous!
I’ll add “theatrical” and perhaps “hallucinogenic” to the adjectives already posted. Thanks to Jimbo and mcncln for posting the additional views.
Indeed- thanks to both Jimbo and mcncln for the additional views. I can’t remember seeing a royal hat (or almost royal hat!) with such a sea creature vibe.
I always got a sea creature feeling that the 2nd hat in the link below could have crawled out of the murky depths and landed on HM’s royal head!
Berlin, 1965:
https://www.dw.com/en/a-history-of-relations-germany-and-the-queen/a-18534971
That’s one whopper of a headpiece! It looks like it’s made of wired ribbons.
SoCal Gal, calling it a “whopper” is certainly an understatement! Haha. How about humdinger, doozy, crackerjack, and corker? Thanks, HQ, this is a great Monday morning eye opener after a hectic anniversary weekend!
Scroll down to see a different shot. (I hope I’m doing this right now. Apologies if I’m not.)
http://razesalib.blogspot.com/2010/07/soraya-esfandiary.html
This view shows that the trailing parts of this flamboyant headpiece are even resting on Soraya’s back and shoulders. Embed from Getty Images
From what I read of the film’s storyline, Soraya’s character in this scene is that of a wealthy jetsetter who is attending a society ball — complete with liveried footmen https://www.shutterstock.com/editorial/image-editorial/tre-volti-i-1964-5864209a. The film’s costumes (and presumably the headpiece) were under the directorship of noted costume designer, Piero Tosi. I regret to say that the way the princess is holding that cloak does remind me of a chorus performer who is trying to preserve her modesty while wearing a skimpy costume – e.g. a Wagnerian Rhine-maiden – though I doubt that was the designer’s intention.