Princess Eilonwy is a twelve-year-old girl with flowing blonde hair and a delicate figure. In the film, Eilonwy is portrayed as plucky, cynical, and talkative, as shown by her tendency to go off into rants at Taran for seemingly trivial reasons (though he can be snippy back in their mutual antagonism).
Despite her naturally strong-willed personality, she can be affectionate (for she tries to get Taran's spirits up in one scene and seems fond of Gurgi) and emotional, as shown by her anxiety after escaping from the Horned King's castle and her genuine sadness at Taran's near-sacrifice during the film's climax; by the end of the movie, Eilonwy has dropped her defenses significantly and she and Taran begin to be romantically involved.
Eilonwy appears to be addled once she first appears, confused and thinking her reasons of being imprisoned in the Horned King's castle vague.
Eilonwy is slender and fair-skinned. She has pink lips, blue eyes, blonde hair from her head to her buttocks, black band on the back of her hair, pink dress with dark violet bodice and white long puffy sleeves, white petticoat and black shoes.
Eilonwy appears to have magical capabilities, which is what saves both Taran and Fflewddur from the Horned King's prison.
The Black Cauldron
In the film, the Horned King takes her hostage in hopes that her magic bauble could find the Black Cauldron. She and Taran first meet in the lower ruins under the Horned King's castle (once the home of King Rhitta), when the addled princess is searching around and attempting to find a route to escape.
Instead of leaving, Eilonwy allows Taran to come with her and escape from the Castle. There, the two come across the mystic sword, Dyrnwyn (and Eilonwy expresses vague disgust at Taran merely taking a sword from a dead body) and free Fflewddur Fflam from his imprisonment. The group of friends later travel to the realm of the Fair Folk (thanks to Gurgi, who didn't lie to Taran and the gang) and reunite with the pig Hen Wen. The king of the Fair Folk sends Doli with them as an escort to the Marshes of Morva to retrieve the Cauldron.
After they receive the Cauldron by trading away Dyrnwyn (which Eilonwy briefly protests against), they are captured again by the Horned King who then unleashes the Cauldron Born. Taran prepares to sacrifice himself, shocking Eilonwy, who insists he reconsider, though Taran claims he has already made his decision, without her elaboration on it. After Gurgi takes over and sacrifices himself into the Cauldron, the friends trade the Cauldron back to the Witches of Morva in exchange for Gurgi back. The bargain is granted, and Eilonwy and Taran end up kissing each other.
During the release of The Black Cauldron, Taran and Eilonwy were walk-around characters at the parks. So far, they have never returned to the parks. A mural also appeared at the now defunct restaurant Gurgi's Munchins and Crunchings.
- Eilonwy is a major character in The Chronicles of Prydain book series by Lloyd Alexander, upon which the film was loosely based.
- Eilonwy is not included the Official Disney Princess line-up or in any of the merchandise. This is most likely due to the film's poor performance at the box office.
- Princess Eilonwy has been nicknamed by fans as the "Forgotten Disney Princess" because of her little-known status and the fact she is not an "official" Disney Princess, despite being a princess by birth.
- In the novels of The Chronicles of Prydain, Eilonwy had a habit of running around barefoot. Pre-production artwork for The Black Cauldron shows that the Disney's version of Eilonwy was to be barefoot as well.
- In The Chronicles of Prydain Eionwy's bauble does not float, nor does it change its colour from anything other than the golden light it gives. It is also unbeknownst to Eilonwy herself but in the series, her bauble's real title is The Golden Pelydryn.
- Another distinction from the movie and original series is that Eilonwy is a descendant from the Welsh mythological god, Llyr.
- Since she was changed to wearing shoes, Eilonwy is one of the few human heroines to not be seen barefoot in any of her media. She has this in common with Snow White, Alice, Belle, and Merida.
- The character of Eilonwy in the books is described as having red-gold hair, but she is a blonde in the film.
- Unlike most Disney princesses and heroines, only Eilonwy and Kida possess a magical item instead of animal sidekicks.
- Eilonwy bears a resemblance to Princess Aurora in that they have long blonde hair.
- If Eilonwy joins the Princess franchise, she will take place as the youngest princess (she is 12), a title which currently belongs to Snow White.
- She has similarities with Princess Odette from The Swan Princess. Both have thick blonde hair and similar facial expressions. Their facial structures are similar too, though Odette's are more mature due to her being older.
- Hayley Mills was originally cast for the role of Princess Eilonwy, and got to record some scenes, more for reasons unknown, she was replaced.
- In some products, the color of her dress is blue. This is similar to the case of Wendy Darling, whose blue nightdress is seen as pink in books and film posters.
- Despite its lack of success in the theaters, there has been a recent influx of older generation fans who love her, and are trying to revive her for newer generations on DeviantArt, Tumblr, and other social sites.
- At Royal Prep, there is a figure on the clock tower that is very similar to Eilonwy, but could also be Aurora, or the grandmother of Roland II, who likely had blonde hair that her grandson would partly receive.
- Eilonwy's name was coined by the author Lloyd Alexander based on Welsh names with elemental meanings such as white brow or elm. Eilon means "fawn" in Welsh, while the suffix -wy means "water".
- Although she was revealed to be taken by the Horned King prior to her meeting Taran and her first appearance in the movie, Eilowny's kidnapping alone was never seen on-screen.
- Eilonwy's parents are never seen. The novels state that her parents are already dead. This would make her an orphan - just like Taran.