Barbara Joanna Miller, known on the Island by her middle name, was a Flight 815 survivor who drowned on Day 6 while swimming in the ocean. She was referenced in two episodes ("White Rabbit") ("Born to Run") (being depicted only briefly in a photograph in the latter) and was also mentioned by both the the official novelization Secret Identity as well as the ABC website's Lost diary by Janelle Granger.
Before the crash
Joanna was an experienced diver and swimmer. She was known to Janelle on the Island as they went swimming together in Australia, and made sure they sat next to each other on Flight 815. Janelle was upset at her death, suspecting foul play. (Janelle's diary)
According to the eulogy by Kate, Joanna wasn't actually supposed to be on Flight 815. She was scuba diving off the barrier reef, got an ear infection, and was grounded for two days by her doctor. She bumped her flight and ended up on Oceanic 815. ("White Rabbit")
On the Island
Day 6 (Season 1)
Joanna was caught in a riptide during a morning swim six days after the crash. Both Boone and Jack made attempts to save her. According to Janelle's diary: "It just doesn't make sense. She was smarter than that - she knew about the rip tides and how to swim parallel to the beach.". She died because Jack first reached Boone (who was also drowning) and brought him to shore rather than go directly for Joanna. Jack felt remorse at the fact that he had never spoken to Joanna, and couldn't believe she had died. ("White Rabbit")
Some fans believe that Kathleen O'Neill, a middle section background extra, bears a strong resemblance to the photograph on a burning passport of Joanna Miller shown in "Born to Run", although this assertion has not been confirmed. In support, O'Neill has not been positively identified in the background of scenes after Joanna's death in "White Rabbit". However such an appearance on the passport prop would not necessarily signify a canoncial storyline correspondence of O'Neill with this character by the Lost writing team.
- Joanna also appears in the Lost novelization Secret Identity and was good friends with the main character, Dexter Stubbs.
- The flight manifest from the German website, 108minuten.de, states Joanna's full name as Joanna Ranting. However, that manifest is an expanded and partially corrected version of the manifest from the Lost: The Untold website, and since both versions of the manifest contain numerous details that directly contradict information stated on the show itself, they're considered non-canonical.
- In "Born to Run", Joanna's passport was shown to have the name "Barbara Miller" on it, and the name Joanna was nowhere to be seen. It is then widely believed that her full name is "Barbara Joanna Miller", and that Joanna is her middle name. This is eventually confirmed in the Lost Encyclopedia.
- Joanna's Passport number starts with HNSO. HNSO also appears in Ben and Michael's Fake Passport numbers.