Shanna O'Hara Plunder is the daughter of a diamond miner named Gerald O'Hara. Born in Africa, she spent the majority of her childhood growing up in the jungles of Zaire. At the age of six, her father went to kill a rogue leopard that belonged to her mother, Patricia O'Hara. While hunting for the leopard, Shanna's father accidentally killed her mother. This traumatic incident led to Shanna's lifelong crusade against the use of firearms. After the incident, Shanna moved back to the United States to live with relatives. Shanna grows up to become an accomplished Olympic athlete, specializing in competitive swimming and track and field. She then became a licensed veterinarian.
After completing college, Shanna began to work for the Central Park Municipal Zoo in New York City as a zoologist. While working at the zoo, Shanna raised many animals, including a female leopard named Julani. During this period another shock to her system came when Julani was shot and killed by a zoo guard. The following day, the zoo director proposes Shanna take Julani's cubs, Ina and Biri — Yoruba names meaning "bright" and "black", respectively — to the Dahomey Reserve in Africa.
While in Africa, Shanna becomes more attuned to nature, patrolling the jungle and living freely in the wild lands. She begins to wear Julani's fur pelt as a sight-and-sense cue to help with the raising of the cubs. In the jungle, Shanna becomes more and more at home with herself and her new native element, all the while protecting the reserve from poachers as Shanna the She-Devil.
During her stay in Africa, her father is kidnapped by the Mandrill. Shanna searches for him until the wizard Malgato kidnaps her to Antartica's Savage Land, a prehistoric jungle. She escapes with the help of Lord Kevin Plunder, a.k.a. the jungle lord Ka-Zar. Shanna returns to Africa to look for her father, and learns he was killed by the Mandrill. Seeking revenge, she goes to America to aid Daredevil and Black Widow in stopping the Mandrill and Nekra's plan to overthrow the American government.
After this, Shanna travels between San Francisco and the Savage Land, finally returning to Africa. Only to find Ina and Biri have been killed by a religious cult leader, Raga-Shah. After a short grieving period in America, Shanna tracks and kills Raga-Shah. Around this time, she begins therapy with psychologist Dr. Dorothy Betz.
Later she moves to the Savage Land, where she and Ka-Zar fall in love, marry, and have a son, Matthew. Shanna and her husband fight to protect the quality of life of all natural habitats from the encroachments of the modern world.