Sil is a fictional character from the Alien franchise, first appearing in the 1995 film "Species." She is a genetically engineered hybrid created from human and alien DNA, designed to possess both human intelligence and alien abilities. In the film, Sil escapes from a research facility and embarks on a quest to find a mate, driven by her biological instincts. Her character explores themes of identity, humanity, and the consequences of scientific experimentation, making her a complex figure within the science fiction genre.