Dr. Ellie Degler, formerly Ellie Sattler, was a paleobotanist and colleague of Dr. Alan Grant. She was also his girlfriend for a short time, and they went on many digs together. When Grant was contacted by John Hammond, the InGen CEO invited her along as well, needing the opinion of a paleobotanist. Once on Isla Nublar, Ellie discovered a species of plant that had been exctinct since the Cretaceous period. She quickly found something more interesting to focus her attention on, however - a living, breathing Brachiosaur.
Like Grant, Ellie was awed and entranced by the dinosaurs that InGen had created, but only at first. She too soon realized the dangers posed by Jurassic Park, especially in the plants. Many of the plants displayed in the visitor's center, chosen by Hammond for beauty, were actually poisonous. This implied that Hammond and InGen were ignorant of the long-gone ecosystem in which these animals came from, and knew little about the organisms they had created. When they went on the park tour, Ellie stayed behind to help the park vet Dr. Harding with an ailing Triceratops, while the others went on ahead back to the visitor's center. This probably saved her life, as she was not present when the Tyrannosaurus Rex escaped its paddock due to a power loss, and attacked the Explorer tour vehicles.
After being dropped off back at the visitor's center by Dr. Harding, Ellie returned to the wreckage of the Explorers with game warden Muldoon. All they found were the remains of Donald Gennaro and a badly injured Ian Malcolm; Grant and Hammond's grandchildren were nowhere to be found. Later, with the help - and sacrifice - of Muldoon, Ellie was able to access the park generator shed and restore the power, allowing Lex Murphy to boot up the phones to call for help. Reunited with Grant, she escaped the island with him and the other survivors.
Some years later, Ellie and Grant broke up for unspecified reasons, and she married a man named Mark Degler. They had two children, including three-year old Charlie. She and Grant still kept in touch and remained friends, however. When Grant and the Kirby family became stranded on Isla Sorna, Ellie came to their rescue. She used her husband's connections in the State Department to send the U.S. Navy and Marines to Sorna, saving them.