The swan maiden is a mythical elf creature who ususally shapeshifts from human form to swan form. Despite the name, males are found in a small number of legends. The key to the transformation is usually a swan skin, or a garment with swan feathers attached.

In folktales of this type, the male mortal character spies the immortal maiden typically by some body of water (usually bathing), then snatches away the feather garment (or some other article of clothing), which prevents her from flying away (or swimming away, or renders her helpless in some other manner), forcing her to become his wife.