Very little is known about Carole. Claire said she was a librarian. About 23 years prior to the events of "Par Avion", Carole had an affair with Christian Shephard. It is unknown how long it lasted, but Carole became pregnant with their daughter, Claire. Christian supported her and the baby, came down to visit several times, and he even paid for her house's mortgage. However, neither Carole nor her sister Lindsey approved of Christian dividing his time between families, and they made him promise never to come back.
Carole decided to tell Claire that her father was killed when Claire was two, and she proceeded to raise Claire by herself, working as a librarian. Unfortunately, Claire became angry and reclusive, adopting a Goth-like lifestyle. Claire later commented that she was "horrible" to Carole. ("Par Avion")
Accident and coma
Carole and her daughter were driving down a freeway when they had a ferocious argument. Claire shouted that she hated Carole and that she wished she was dead. She was speeding when she hit a truck and was forced off the road. Carole, who was not wearing her seat belt, was thrown through the windshield and she landed hard on the pavement. Though the doctors were able to save her life, she was left in a coma. Christian immediately flew down to see her, and he paid for all of her hospital expenses. He introduced himself formally to Claire as her father, and he suggested, reluctantly, that she be taken off life support, since there was no hope of her recovering or ever leading a normal life again. ("Par Avion")
Claire decided that she could not go through with it, and Carole was kept alive for many years. (That statement is repeated on numerous sites despite Claire's observation to Thomas in "Raised by Another" in 2004 that "(her) mum would disown (her)" to which he replies "she basically has already".) She was still in the coma when Claire became pregnant and Claire visited her regularly, watching nature programs with her mother. While Carole was in a coma, Claire tearfully apologized to her mother for putting her in her current condition, and told her about the adoption of her then-unborn grandson. ("Par Avion")
After the rescue of the Oceanic Six
Carole somehow recovered from her coma sometime after the crash. After the rescue of the Oceanic Six, she attended the funeral of Christian Shephard. She then spoke to Jack after the funeral, revealing to him that she had an affair with Christian, and that their daughter, Claire, was Jack's half-sister and was on the plane with Jack. As Jack tries to maintain his calm, she apologizes and leaves. On her way out, she notices Kate holding Aaron, and notes that the baby is beautiful, ironically not realizing that she is commenting on her own grandson. ("There's No Place Like Home, Part 1")
Sometime after the return of the Oceanic Six, Carole Littleton sued Oceanic Airlines. In 2007 she settled with them and traveled to Los Angeles to pick up her check, which was delivered by Dan Norton. Having followed Norton to Carole's hotel room, Jack confronted her, believing her to be Norton's mystery client seeking custody of Aaron. At this point she revealed that she did not even know Aaron existed, much less his status as her grandson. ("The Little Prince")
Before going back to the Island, Kate went to see Carole with Aaron. Carole was confused as to why Kate saw her, and mentioned her visit with Jack. Kate tearfully confessed that Aaron was really her grandson, that her daughter survived the crash, and declared that she was going back to save Claire. Carole took the news well, and Kate took her in to see a sleeping Aaron. Aaron remained with his grandmother while Kate left to go see Jack. ("Whatever Happened, Happened")
Sometime later Kate returned from the island, fulfilling her word that she would return with Claire.
- The role of Carole Littleton in "Par Avion" was played by Arlene Newman-Van Asperen, though she had no lines and was therefore considered an "extra". For Carole's appearance in "There's No Place Like Home, Part 1", however, a new actress, Susan Duerden, was cast, since this was an actual acting part.
- The casting description for Carole's part in "There's No Place Like Home, Part 1" was Donna - Caucasian, blonde, pretty, Australian. Has had to deal with many set-backs in her life but is strong and has persevered. Now has to deliver painful and emotional news...Must be authentically Australian or be able to do an impeccable Australian accent  The alias was likely chosen to avoid spoiling Carole's appearance in the episode before the part was even cast, and is common for casting on the show.
- This character is incorrectly credited as "Carol Littleton", missing an "e" at the end of her first name, in the press release for "Whatever Happened, Happened". 
- Out all of the main characters. Carole has only met Claire, Jack, Kate and Christian.
- For fan theories about these unanswered questions, see: Carole Littleton/Theories