Annette Charles -- who played Cha Cha in the 1978 movie "Grease" -- died last night in her Los Angeles home ... her rep tells TMZ.
Her rep tells us, she passed away due to complications from cancer.
The family is planning to release a full statement within the next 24 hours. Annette was 63.
A family member tells us, "Annette had recently started having difficulty breathing ... and when she went to the doctor she learned that she had a cancerous tumor in one of her lungs."
We're told doctors only learned about her condition a few months ago.