According to all online sources she was born Hélène Stoliaroff (or Stoharoff) in Deauville, France on June 12th 1941. Some sources say she is of Russian descent and that she had a sister, Nicole. She is still living at the time of writing.
I have found mentions in books that she started out as a teenage model in France. Hélène began her acting career with appearances in two French films in 1959, one a small role, in the other, Détournement de mineures, she played the lead. It appears that she originally intended to use the name "Chancel" as her pseudonym, but adopted "Chanel" instead after it was mis-spelled in the Italian publicity for the film.
It would seem that she caught the eye of Italian star Ugo Tognazzi, who she appeared opposite in 6 films between 1960-61, graduating from supporting roles to playing the female lead in Tu che ne dici? I think it is safe to assume that she relocated to Italy at this time, where her career was based from then on. She also became romantically linked to Tognazzi, which is verified by many images of the pair to be found online and is mentioned in the biography on Tognazzi's official website.
While she continued to play comedic roles throughout her career, from 1961 she also began appearing in more dramatic parts, notably in the peplum genre where she became one of the genres most in demand stars. When the popularity of peplums declined in the middle of the decade she remained a popular draw in major roles in eurospies and spaghetti westerns, on a few occasions using the pseudonym "Sherill Morgan". Additionally she also made some appearances in fotoromanzi during this period.
Sadly from the start of the 70's, like many actresses of her generation, the size and quality of her roles declined. She soldiered on through most of the decade, finally calling it a day with her last known appearance being in Mogliamante in 1977, at the age of 36. She confirmed in a recent TV interview that her reasons for retirement were similar to the reasons given by Rosalba Neri, in that she was unhappy with the variety and quality of the roles she was offered.
Not much is known of her life following her retirement, but one article I found says that she ran a "thriving tourist business" with her husband. She does maintain a low-key presence on Facebook under her real name (and is a member of my Peplum Paradise group there). Since it seems she prefers to maintain her anonymity with only a small group of online friends, then I will respect that and will not provide links. Her profile picture shows that she is still beautiful after all these years.
I think it is unlikely that there will be much to be found in the way of undocumented appearances, but I have been proved wrong in the past so remain optimistic to the possibility.
Note: like the spelling of her name, the accents above the "E"'s in her name seem to change very randomly among her credits - many films omit them completely. I haven't included these variations as being spelling differences, but they can be seen in the screen shots provided throughout her topic for anyone interested.
- Détournement de mineures .... Christine (credited as "Hélène Chancel")
- Les dragueurs .... Party guest (credited as "Hélène Stoliaroff")
1960 - Genitori in blue-jeans .... Nuri (credited)
- Il mio amico Jekyll .... Rossana (credited as "Helen Chanel")
- Le olimpiadi dei mariti .... Elke (credited)
- Tu che ne dici? .... Stella (credited)
- Un dollaro di fifa .... Alice Perkins (credited)
1961 - 5 marines per 100 ragazze .... Elena (credited)
- Gerarchi si muore .... Italia (credited)
- La ragazza sotto il lenzuolo .... Dolly (credited)
- Maciste alla corte del Gran Khan .... Liu-Tai (credited)
1962 - Colpo gobbo all'italiana .... French tourist (credited)
- I tre nemici .... Jacqueline (credited as "Helen Chanel")
- La monaca di Monza .... Catarina (credited)
- Lasciapassare per il morto .... Hélène (credited)
- Maciste all'inferno .... Martha Gaunt / Fania (credited)
1963 - Avventura al motel .... Madame de Sèvres (credited as "Helen Chanel")
- L'invincibile cavaliere mascherato .... Carmencita (credited)
- La donna degli altri è sempre più bella .... Donna Rossana (credited)
- Le verdi bandiere di Allah .... Rosalana (credited)
1964 - Due mafiosi nel Far West .... Betty Blanc (credited)
- Ercole, Sansone, Maciste e Ursus gli invincibili .... Astra (credited)
- Il dominatore del deserto .... Zaira (credited)
- La valle dell'eco tonante .... Farida (credited)
1965 - Asso di picche - Operazione controspionaggio .... Pat (credited)
- Il conquistatore di Atlantide .... Queen Ming (credited)
- Le notti della violenza .... Carla Pratesi (credited)
1966 - Agente segreto 777 - Invito ad uccidere .... Jeanne Cartier (credited)
- Duello nel mondo .... Mary Brightford (credited as "Sherill Morgan")
- Ischia operazione amore .... Beatrice Dinelli (credited)
- L'arcidiavolo .... Clarice (credited as "Sherill Mogan")
- Le piacevoli notti .... Violante (uncredited)
1967 - Cjamango .... Pearl Hernandez (credited)
- Con lui cavalca la morte .... Dolores Talbot (credited)
- Due rrringos nel Texas .... Sentenza Jane (credited)
- Il coraggioso, lo spietato, il traditore .... The woman (credited)
- Killer calibro 32 .... Dolly (credited as "Sherill Morgan")
- Nel sole .... Ivana Vannucci (credited as "Helen Chanel")
1968 - 7 uomini e un cervello .... Georgette (credited)
1969 - La legge dei gangsters .... Contessa Elena Villani (credited as "Elene Chanel")
- La morte bussa due volte .... Angela (credited as "Helen Chanel")
- Un posto all'inferno .... Betsy (credited as "Helen Chanel")
1970 - Edipeon .... Brothel keeper (credited)
- La ragazza del prete .... TV presenter (credited)
1972 - Boccaccio .... Princess of Civigni (credited as "Helen Chanel")
1973 - Gli amici degli amici hanno saputo .... Suzette (credited)
1975 - Labbra di lurido blu .... Elli's mother (uncredited)
- Lo sgarbo .... Lady White (credited)
1976 - Il bocconcino .... Michela (credited as "Elene Chanel")
- Stangata in famiglia .... Corinne (credited as "Helen Chanel")
1977 - Mogliamante .... Landlady (credited as "Helen Stoliaroff")