Beautiful, gracious, elegant yet fragile

At the end of the tale of the Ugly Duckling the duck turns out to have been a swan all along.
The composition Schwanengesang. The ballet Swan Lake. The Swan Princess. Seven Swans. Female characters in fiction tend to have the surname "Swan" to imply their beauty. Examples are Elizabeth Swann and Bella Swan.
The Dying Swan is a very popular ballet dance, based on the idea that a beautiful creature like a swan is also mortal.
The word "swan song" also refers to the final masterpiece by a creator.