Jill Smith is a pre-existing, playable Sim that comes with The Sims 2 game. She is a child and lives with her family - parents and older brother - in Strangetown.
She, her brother, her unborn cousin, and her half sisters/aunties are all Sim-Alien Hybrids.
Despite being half alien and could be equivalent to those children of an alien abduction, Jill has no distinguishing features of this race. She has the pale skin, blonde hair, and green eyes of her mother, a human (so she is like Dina and Nina Caliente). She is friends with Buck Grunt, despite a family feud between the Grunts and her family.