Dawn Lyn -- a former child star on the TV show "My Three Sons" -- is fighting for her life after undergoing brain surgery and falling into a coma ... this according to her former costars.
Word of Lyn's condition first cropped up on social media through posts from people like Stanley Livingston and Tina Cole ... who starred opposite her back in the '60s and '70s when their sitcom was on the air.
Livingston wrote, "Just found out my little TV Sis', DAWN LYN (Dodie), is in a COMA and fighting for her life. She had surgery recently to remove a brain tumor. Please pray for her to have a swift and full recovery. I took Dawn out to lunch a couple of months ago. We had a great time reminiscing about our MTS days. Dawn is one of the nicest human beings I have ever known. Thoughts and prayers also go out to her husband, John, at this time. This is devastating news!" Stanley played Dawn's TV brother, "Chip" Douglas.
Cole addressed it as well, saying ... "My heartfelt prayers go out to my "My Three Sons" sweet "lil' sis", Dawn Lyn (Dodie) and her husband John. Dawn is fighting for her life after undergoing brain surgery."
She adds, "I'm in touch with John and I will keep you all updated. Please keep her in your prayers as well."
Lyn's real-life blood brother, Leif Garrett tells TMZ ... "My sister, Dawn, never wanted anyone to know about the surgery. Since it has been leaked on social media, I would really appreciate everyone’s understanding that it has already been a difficult time having lost both of our parents and a cousin recently."
Leif also says, "Please just keep my sister in your thoughts and prayers and respect our family’s privacy. Thank you."
While Dawn is certainly most famous for her role as Dodie Douglas during the last 3 seasons of 'MTS,' she went on to do more ... including voice acting work, additional TV roles and even some films here and there.