Holly Marshall is the daughter of Rick Marshall and the sister of Will Marshall. She is the youngest human in the Land of the Lost. She is often seen wearing a red checked shirt with brown pants. She also wears her blonde hair in a pig tail. She is very smart and can normally figure out everything in the Land of the Lost. Due to her age, she is usually frightened at most problems, and also has mild acrophobia (fear of heights). Her and her brother fight sometimes but when the problem gets tough they are able to work together. She saved Will from the Sleestak God once and got a scar from it. Holly is very kind to the animals of the Land of the Lost, and can speak the Pakuni Language. She befriended Dopey and adopted him as a temporary pet. Her chores include: cooking, cleaning, and watching the cave. She has been ridiculed about her cooking. According to Rick she looks like her mother. Before the Marshalls went on their routine expedition, Holly was a very smart child. She lived in Indianpolis. Her mom died in an unknown accident. She then lived with her Dad and her brother, Will. She then decided to go on the trip that they were planning. This directly leads into the Land of the Lost. In the Land of the Lost, Holly has been scared about most of the problems that have come up, but has mainly been strong about her decisions. Holly, has been hit by almost everything. She has been captured by the Sleestak, the Zarn and a mysterious red ring that drains the energy from the creatures that wear it. Holly has named almost all of the dinosaurs that the Marshalls come across.
Holly meets a future version of herself named Rani. Rani is about ten years older than Holly and has the same scar on her lower arm that Holly had recently acquired, thus confirming her identity. This strongly suggests that she and her family eventually do get home. But since the future is always in flux, nothing can be assured.