Helen Cartwright is a main character and one of the two deuteragonists of NiGHTS: Journey of Dreams. Like Claris Sinclair, she also has a music-related dream, though she plays the violin rather than singing. She is from Bellbridge and her favorite hobby is playing the violin.
Helen has dishwater blonde hair tied in a ponytail with a pink hair-tie, blue eyes, and pale skin. She wears a white long sleeved ruffled shirt with a big collar, a pink long-sleeved coat opened with curving collars, a blue slightly pleated skirt with a thin white laced hem, black knee-down pants with white cuffs, red shoes with yellow details and brown straps and soles, and white socks.
At the concert, Helen wears her hair down and wears a short-sleeved magenta dress with a pleated skirt and bow at the waist with her light pink jacket and dark pink spots. She has a light purple hairclip, as well as a red rose. She also wears magenta shoes.
Helen's story begins with her and her mother playing violin together. Suddenly, Helen's cellphone (or similar device) rings. Apparently, her friends are calling her. She apologizes to her Mom and puts the violin down, running off to go hang out with her friends. Her mother looks sadly down at the nearby calendar: it's only a week or less until Helen's violin recital. In the next scene, Helen is walking down the street with her friends eating ice cream (one girl is named Sabrina, a red-head who holds a vague resemblance to Claris, and the other is named Caitlin, who has brownish-black hair and white clothing). As they're walking and laughing, Helen looks in one of the shop windows and sees violins. She stands there a moment looking sad and thoughtful; she turns away, quietly apologizing to her mother for running off during practice. She sees her mother's reflection in the window looking sad, when suddenly she snarls and turns into a monster and the window breaks, Helen falls back to see her two friends morph into smoke-like monsters. Helen, frightened, runs away. As she runs, she sees a bright light in front of her and spreads out her arms.
Helen wakes up crying, picking up a leather journal on her bed as she sits up. Helen hugs it, thanking NiGHTS silently. Then she nods her head and notices her white violin case on the floor beside her bed. The scene changes outside to large building in the city, where her mother is awaiting her, looking worried in a blue outfit, carrying a brown violin case. Helen comes rushing up the steps to her, in a different outfit, panting and carrying her violin case. Her mother says her name happily in relief, and Helen stands up and pulls her ponytail down, swinging her hair slightly and smiles then winks. The scene changes to a concert hall with a crowd of people in the audience. Helen and her mother are without their jackets playing violin on stage. Helen has a rose in her hair. The two play with the background piano music, moving side by side and playing without hesitation. Helen feels herself enjoying the recital, and as she slightly swings around, she changes back into her normal outfit flying in Bellbridge towards the moon with her eyes closed. As the recital ends, the audience claps loudly, and Helen and her mother bow. Sabrina and Caitlin are spotted cheering for her in the crowd wearing beige clothing. Helen smiles and puts her arm around her mother's and leans on her gently to her mother's surprise. Helen's mother then looks up to the crowd and puts her arm on her daughter's hand.
Helen is very proper and pleasant, being very formal when first meeting Owl and NiGHTS in Nightopia. She is a very feminine young lady with a fondness for music and the color pink. She is also a bit of a scaredy-cat, being frightened by the harmless Octopaw, as well as loud noises and darkness.
Helen is shown to live in a very large home and since her recital held a lot of people in attendance, this may indicate that Helen is from a wealthy family and that she or her mother is well known.
Still a young girl, Helen finds spending time with her friends more appealing than practicing with her mother. She loves her mother very much, but as Helen continuously shuns lessons and disappoints her mother, her guilt grows. She fears to make a mistake during her recital and is plagued by guilt for being so careless while her mother practices dutifully. This drives her to have nightmares and makes her a target for the Nightmarens to take her Ideya.
Her dream worlds are beautiful places or have a strong aesthetic; an ocean ruin, a world made of glass and a beautiful forest. According to NiGHTS, each dream represents a part of Helen's heart, so when she believes a world of glass, it is fragile, meaning that she feels that way about herself.
When Helen accepts her mistakes and vows to protect what is really important to her, she gains renewed courage. In the waking world, she performs at the recital with confidence, pleased to have conquered her fears, impressed her friends, and strengthened her relationship with her mother.
Many of Helen's dreams are based on calm, feminine, relaxing places.
Helen's bosses seem to be female related, such as Bomamba and Queen Bella. However, Girania appears to be more like a male, being a large fish (and when the player battles it for the last time, it has strange ornaments). Still, despite this, Girania has been taken in pretty much as a female differently.
Aqua Garden is based on the gentle, pure side of Helen's heart. Aqua Garden is where Helen's White Ideya is hidden. The boss of this dream is Girania.
Crystal Castle is based on the fragile side of Helen's heart. Crystal Castle is the first place where Helen meets Will, making the Mission 3 where she leads Will out of the castle in a maze. Crystal Castle is where Helen's Blue Ideya is hidden. The boss of this dream is Bomamba.
Memory Forest is based on Helen's memories and passion for music. For memories, it is shown how Helen touches a tree in the forest, remembering when her family went on a picnic, following with the situations of Mission 3. For music, Helen and NiGHTS find a concert performed in the sky by hitting the music symbols on the music line to play the song (this is Mission 4). Memory Forest is where Helen's Green Ideya is hidden. The boss of this dream is Queen Bella.
12-year old Helen lives in a quiet, upper-class neighborhood in the great city of Bellbridge. Helen and her mother were always very close, spending their days together, going shopping, studying, picking out clothes, and other such things. Most importantly, Helen learned to play the violin from her mother, starting from a very young age, and she loved it so. After school, the two of them would play together out on the terrace behind her home. Helen's dream was that one day, she would play the violin in concert on stage.
However, as young Helen grew up and started to go from being a little girl to a young woman, her relationship with her mother began to change. She was well-mannered, kind, and popular in school. She had many friends in school, and her social life soon began to take away from her time with her mother- and from the time she spent with that old-fashioned violin, her dream to one day play on stage gradually becoming forgotten. Her feelings for her mother were kept deep inside, though, and subconsciously, she began to feel a deep sense of guilt over the distance that had grown between them, and this guilt manifested itself in the form of recurring nightmares. One night, though, while fleeing from these dark visions in her head, she ended up in a strange new world, where she encountered a mysterious dream-dweller named NiGHTS.
- Helen is 12 years old.
- It is hinted in a few places that Helen comes from an upper-class family, much like Claris Sinclair.
- Helen, like Elliot, Claris and Will, was considered to make an appearance as a racer in Sonic & All Star Racing Transformed, where she'd drive NiGHTS shapeshifted as the car,  however a Nightopian was selected to be the driver over her and the other visitors, if Helen had made into the game, that'd mark her first appearance since her debut in NiGHTS: Journey of Dreams.
- Though this can't be considered an appearance, Helen was indirectly mentioned in the NiGHTS' notification in Sonic Runners, being addressed by the name "unsure young girl".
- Helen seems to resemble Emilia from Phantasy Star Portable 2 and sounds similar to Wendy Darling from the Disney movie Peter Pan and Alice from the Disney movie Alice in Wonderland, though she is not voiced by Kathryn Beaumont.
- Helen might have been named after the second level of the Jungian's animas development.
- Helen is voiced by Victoria Ashby, a Canadian born British voice actress.
- For some reason, in one part of the game while Helen and NiGHTS are in Memory Forest, Helen's voice actress somewhat loses her British voice.