Chicos said the TV producer died on Wednesday morning as a result of her battle with Parkinson’s disease and a recent stroke.
She was 93.
"One Life to Live" and "All My Children," both set in fictional Pennsylvania suburbs, enjoyed lengthy runs on ABC. "One Life to Live," which revolved in part around the Lord family, aired from 1968-2012. "All My Children," which famously starred Susan Lucci as Erica Kane, aired from 1970-2011. Both were later revived as online series.
Nixon's daytime writing credits also included CBS' "Guiding Light" and NBC's "Another World." She received a Daytime Emmy for lifetime achievement in 2010.
Nixon had just finished writing a memoir, "My Life to Live," which is scheduled to be released in January.
Lucci posted a photo of herself with Nixon on Instagram Wednesday, writing, "I am devastated to learn that we have lost Agnes. I adored her and admired her -- and I am forever grateful to her! May this liveliest and loveliest of women rest in peace."
Bob Iger, chairman and CEO of The Walt Disney Company, which owns ABC, said in a statement, “It is with a heavy heart I mourn the passing of television pioneer Agnes Nixon, someone I was proud to call a friend. Agnes’ impact on daytime television and pop culture is undeniable. She was the first to champion socially relevant topics, and the towns and characters Agnes brought to life leave an indelible imprint on television that will be remembered forever. On behalf of Walt Disney and ABC, I want to extend our deepest condolences to her family."