Katherine "Kate" Fitzgerald is a major character in the 2004 novel "My Sister's Keeper," a frail teenage girl who was diagnosed with promyelocytic leukemia at a young age. She is the older sister of Anna, and the middle child out of all three Fitzgerald siblings. She sometimes finds all the attention on her stifling. One of the few times that Kate experiences being a typical teenaged girl is when she dates, and has her first kiss with a boy named Taylor. Kate supports the feelings of her younger sister, Anna, and is thankful for the bodily donations Anna has been made to give her throughout her lifetime. At the end of the novel, Kate is revealed to be the one who asked Anna to sue for medical emancipation, because, fed up with the awareness of how much she took from her and the rest of their family, she wanted, for once, to be the sister who protected the other one.
In the original book, Anna is emancipated but dies in a car crash, leaving Kate to gain her organs anyway. Kate eventually grows up to be a ballet teacher, but never forgets her sister and lives with the grief and gratitude for the rest of her life. In the 2009 film adaptation, Kate dies of her leukemia.