Lady Margaret (nicknamed by Gerry Harding) was the alpha-female Triceratops in Jurassic Park: The Game. She is first seen in the Welcome to Jurassic Park scenario, when Gerry and his daughter Jess are looking at the herd. The size of a fully-grown African Elephant, Gerry mentions that she is extremely protective of the younger members of the herd, perhaps acting like a mother to them.
This claim of Gerry's is later put to the test when Margaret is later seen attacking Gerry and Jess, mistaking them as a threat to one of her calves nicknamed Bakhita. She charges through the gate. In Triceratops Trouble, she attacks the car until Jess stops the damaged car horn from making constant noise.
Later on, the Tyrannosaurus rex (nicknamed Rexy) arrives in the scene, and the two giants start fighting. It is unknown whether she survives from the fight with the T. rex, as only one of her horns is left on the ground the next morning. It's believed that both dinosaurs had withdrawn from the battleground, as the Tyrannosaurus would not have been hungry enough to want to pursue several humans, a Parasaurolophus and a Raptor if it had killed and eaten the alpha. As well as the fact that, if the Tyrannosaurus rex had killed Lady Margaret, Gerry and Jess would probably have seen her entire half-eaten corpse instead of just a horn.
It is unknown what happened to her after the Isla Nublar Incident of 1993.